This file is to show what I did to convert the plplot
svn SourceForge repo to a SourceForge git repo following closely
what I did for a similar conversion of timeephem.  This is
a preliminary conversion, and it is likely that if I can get
it to work, Hazen will do the final conversion.

* Create local directory corresponding to the complete SF svn repo.

svn checkout https://svn.code.sf.net/p/plplot/code plplot_complete_SF_svn

* [Not done by AWI.  Should be done by Hazen.] Turn off write permissions for
  subversions repo and change the display name for that repo from
  "Code" to "Old Code".  To do this, login to SF, --> project page for
  plplot --> admin --> tools.  Then click on the permissions button
  for "Code" to not allow anyone write access.  Then click on the
  label button for "Code" to change that to "Old Code".  N.B. MAKE
  ABSOLUTELY POSITIVE YOU DO NOT HIT THE DELETE BUTTON.  That would
  destroy our subversion repository which we would like to keep
  available at SourceForge for some time in a readonly status

* [Not done by AWI.  Should be done by Hazen.] While in the same location create
  an empty git repo.  Click on the git button, and choose a label of
  "Code" and a mount point of "plplot".  This will create a "Code"
  area at the end.  Drag and drop that area to place "Code" before
  "Old Code" to affect the order of the menus at the SF project page.

  N.B. If you make a mistake with the git repo (like I did with the
  airwin user name for the timeephem case) you can always hit the
  delete button for the git repo to completely remove it from
  SourceForge.  Then start over with an empty repo as above.  But be
  extremely careful which delete button you hit since you could also
  completely remove the subversion repository this way if you do that
  on "Old Code".

* Copy SourceForge svn repo to local disk.

rsync -av --delete svn.code.sf.net::p/plplot/code/* plplot_svn_repository

* Compare a local directory corresponding to this local repo with a
local directory corresponding to the SF repo. Note, for final
comparisons between git and svn we will do much more extensive check
of various revisions

svn checkout file:///home/software/plplot_svn/svn2git_conversion/plplot_svn_repository plplot_complete_local_svn

# Confirm empty differences
diff -Naur --exclude=.svn plplot_complete_SF_svn plplot_complete_local_svn

svn log --verbose plplot_complete_SF_svn >| ChangeLog_complete_SF_svn.log
svn log --verbose plplot_complete_local_svn >| ChangeLog_complete_local_svn.log

# Empty differences except for slight formatting difference (mentioned
# "Changed paths:" for empty tags).  I don't know why there is this formatting
# difference since repos are identical via above rsync, but svn may just
# use slightly different code path for local file repo than it does for remote
# repo.  In any case, differences are slight so I won't worry further about it.
diff ChangeLog_complete_SF_svn.log ChangeLog_complete_local_svn.log

* Analyze overall directory structure of svn repo.

grep "A /" ChangeLog_complete_local_svn.log | grep -v "A /trunk" | grep -v "A /tags" | grep -v "A /branches" | less

Shows that top level directories are branches, tags, trunk, and www, and
within www there are branches, tags, and trunk as well, but only www/trunk is
used. Furthermore,

grep "A /branches" ChangeLog_complete_local_svn.log| grep www

shows no directory called branches/www.

Therefore, I agree with Hazen's decision to treat all of www as a branch.

* Analyze tags.

svn log --verbose plplot_complete_local_svn/tags >| ChangeLog_complete_local_svn_tags.log

grep 'A /' ChangeLog_complete_local_svn_tags.log |less

Shows tags actually appear as subdirectories of tags AND tags/debian.  So
change Hazen rules so that tags/debian/whatever ends up as the git
tag "debian/whatever"

* Prepare files to help conversion

Sources:
http://www.midwesternmac.com/blogs/jeff-geerling/switching-svn-repository-git2svn
http://blog.smartbear.com/software-quality/migrating-from-subversion-to-git-lessons-learned/

  + Find list of author names:

svn log --quiet plplot_complete_local_svn/tags | awk '/^r/ {print $3}' | sort -u

    The above command generated a list that was equivalent to what Hazen
    had already collected in his old authors.txt file.  N.B. Hazen has now
    updated that authors.txt file using real names (such as Alan W. Irwin),
    and it was that rules.txt file I used for my final testing.

  + Update plplot.rules file provided by Hazen for
    PLplot to deal with tags/debian issue.  (Hazen had
    already dealt with /www issue noted above.)

  + Cut and paste from first source above to create the
    svn_tag2git_tag.sh script to be sourced (below) to convert special
    marking of tag-style svn branches to real git tags.

* Do conversion with marked tags as branches.

rm -rf plplot.git  # This removes prior conversion attempts.
time svn-all-fast-export --identity-map=authors.txt --rules=plplot.rules --stats --add-metadata plplot_svn_repository >| svn-all-fast-export.log 2>&1

The time stats were

real    1m0.064s
user    1m11.676s
sys     0m6.760s

  ==> blindingly fast!

  This result took 15 times the time required for the timeephem case
  which seems reasonable since this PLplot svn repository is 15 times
  larger than the timeephem svn repository.

* Check svn-all-fast.log for any error or warning messages.  Some of the tag creations generated warning messages, but as far as I know there is nothing there that looks serious.

* Transform svn branch-style tags to git tags following script given by source 1 above.

pushd plplot.git
source ../svn_tag2git_tag.sh >| ../svn_tag2git_tag.sh.log
popd

 The resulting output file looked reasonable.

* Create clone of local git repo

rm -rf plplot_local_clone.git
git clone /home/software/plplot_svn/svn2git_conversion/plplot.git plplot_local_clone.git

* Tailor script to refer to plplot_local_clone.git and run that script
  to check the PLplot working directory for the local svn repo against
  plplot_local_clone.git

time ./diff_git_versus_svn_tree.sh >| diff_git_versus_svn_tree.sh.out 2>&1

* Create complete git log and check that it looks reasonable.

pushd plplot_local_clone.git
git checkout master
git log --name-status --all >| ../git.log 2>&1
popd

grep '^Author' git.log |sort -u |less

  The results were as expected (i.e. consistent with the authors.txt file
  used for the conversion).

  Also, check which svn revision numbers are in the log.

grep "svn path" git.log |sort --field-separator='=' --key=3 -n |less

  This shows that only 23 are missing, but I think that is reasonable since

grep '^Exporting' svn-all-fast-export.log |grep -v modifications |grep done |less

  (which picks out revisions that created no modifications to git corresponding,
  e.g., to creations of empty directories on svn) had 16 lines leaving
  only 7 svn revisions unaccounted for due to other issues which I didn't bother
  to try and figure out.

[AWI did nothing further in this file so the rest is taken from AWI
experience with timeephem conversion project with all references to
that project replaced by plplot, and all references to airwin replaced
by Hazen's SF username, hbabcock.  Hazen should take each of these
further steps.]

* Configure git with the same information so that the Author lines will
  continue to be consistent in the log for new commits to the git repo.

git config --global user.name "Hazen Babcock"
git config --global user.email "hbabcock@users.sourceforge.net"

* Prepare bare repo for pushing to SF following directions at
  <https://sourceforge.net/p/forge/documentation/Git/>

pushd plplot.git
git remote add origin ssh://hbabcock@git.code.sf.net/p/plplot/plplot
git config branch.master.remote origin
git config branch.master.merge refs/heads/master
popd

* Check remote result:

pushd plplot.git
git remote --verbose
popd

  Which yielded (as expected)
origin  ssh://hbabcock@git.code.sf.net/p/plplot/plplot (fetch)
origin  ssh://hbabcock@git.code.sf.net/p/plplot/plplot (push)

* Push local branches and tags to SF

pushd plplot.git
git push origin master
git push --all origin
git push --tags origin
popd

* Check SF git repo by cloning it than comparing in detail with subversion
  results by using the test script with name of directory
  tailored appropriately in script.

git clone ssh://hbabcock@git.code.sf.net/p/plplot/plplot plplot_sf_clone.git

time ./diff_git_versus_svn_tree.sh >| diff_git_versus_svn_tree_SF_clone.sh.out
less diff_git_versus_svn_tree._SF_clonesh.out

* Enforce workflow with update hook

mkdir git_hooks
cd git_hooks
# edit README file to explain our update hook and
# the workflow policy it enforces.

# This needed to give shell access for 240 minutes before your
# SourceForge shell access disappears again.
ssh airwin,plplot@shell.sourceforge.net create
# Backup original SF updates hook
scp -p airwin,plplot@shell.sourceforge.net:/home/git/p/plplot/plplot.git/hooks/update update_original
cp -p update_original update
# Check permissions (which should be -rwxrwxr-x)
ls -l update
# Edit update file to enforce policy as discussed in detail on the mailing list.
# edit update
.....
# Upload the new version
scp -p update airwin,plplot@shell.sourceforge.net:/home/git/p/plplot/plplot.git/hooks

# Check permissions:
ssh airwin,plplot@shell.sourceforge.net "ls -l /home/git/p/plplot/plplot.git/hooks/update"
# Fix permissions (if required)
ssh airwin,plplot@shell.sourceforge.net "chmod a+x /home/git/p/plplot/plplot.git/hooks/update"

* Tag and remove all branches except master

# List branches
git branch -a

# Tag the branch called branch_name
git tag archive/branch_name origin/branch_name

# Push tags to SF
git push --tags origin

# Delete branches at SF
git push origin :branch-name

# Branch resurrection:
git branch branch_name archive/branch_name

# To get a complete list of remote tags:

git ls-remote --tags origin

# For those who want to make tags and branches on their local repo
# consistent with the remote repo.  (The following command definitely
# gets rid of the local branches that were deleted at SF, but I am not
# sure whether this is sufficient to propagate the tag creations as
# well or whether a subsequent ff-only merge (done as part of the
# normal workflow) of origin/master to master is also required.

git fetch --prune