[PATCH] hg-to-git: handle an empty dir in hg by combining git commits

[Mark Drago <markdrago@gmail.com>]

I had a subversion repository which was then converted to hg and now is moving
in to git.  The first commit in the svn repo was just the creation of the empty
directory.  This made its way in to the hg repository fine, but converting from
hg to git would cause an error.  The problem was that hg-to-git.py tries to
commit the change, git-commit fails, and then hg-to-git.py tries to checkout
the new revision and that fails (b/c it was not created).  This may have only
caused an error because it was the first commit in the repository.  If an empty
directory was added in the middle of the repo somewhere things might have
worked out fine.

This patch will detect that there are no changes to commit (using git-status),
and will not perform the commit, but will instead combine the log messages of
that (non-)commit with the next commit.

Signed-off-by: Mark Drago <markdrago@gmail.com>
---
 contrib/hg-to-git/hg-to-git.py |   15 +++++++++++++--
 1 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/contrib/hg-to-git/hg-to-git.py b/contrib/hg-to-git/hg-to-git.py
index 6bff49b..06e1b41 100755
--- a/contrib/hg-to-git/hg-to-git.py
+++ b/contrib/hg-to-git/hg-to-git.py
@@ -139,6 +139,7 @@ if not hgvers.has_key("0"):
     os.system('git-init-db')
 
 # loop through every hg changeset
+previous_comment = None
 for cset in range(int(tip) + 1):
 
     # incremental, already seen
@@ -159,6 +160,8 @@ for cset in range(int(tip) + 1):
 
     (fdcomment, filecomment) = tempfile.mkstemp()
     csetcomment = os.popen('hg log -r %d -v | grep -v ^changeset: | grep -v ^parent: | grep -v ^user: | grep -v ^date | grep -v ^files: | grep -v ^description: | grep -v ^tag: | grep -v ^branch:' % cset).read().strip()
+    if (previous_comment):
+	csetcomment += previous_comment
     os.write(fdcomment, csetcomment)
     os.close(fdcomment)
 
@@ -181,8 +184,8 @@ for cset in range(int(tip) + 1):
         print 'tag:', tag
     print '-----------------------------------------'
 
-    # checkout the parent if necessary
-    if cset != 0:
+    # checkout the parent if there is a repo to checkout from
+    if hgvers.has_key("0"):
         if hgbranch[str(cset)] == "branch-" + str(cset):
             print 'creating new branch', hgbranch[str(cset)]
             os.system('git-checkout -b %s %s' % (hgbranch[str(cset)], hgvers[parent]))
@@ -210,6 +213,14 @@ for cset in range(int(tip) + 1):
     # delete removed files
     os.system('git-ls-files -x .hg --deleted | git-update-index --remove --stdin')
 
+    # is there something that git will commit (maybe just empty dir was added)
+    stat = os.system('git-status -a')
+    if (stat != 0):
+	print "No changes git notices, will combine log with next commit (maybe empty dir?)"
+	previous_comment = "\n\n--- hg-to-git merged commit ---\n\n" + csetcomment
+	continue
+    previous_comment = None
+
     # commit
     os.system(getgitenv(user, date) + 'git-commit -a -F %s' % filecomment)
     os.unlink(filecomment)
-- 
1.5.2.4