use the last commit in which debian/changelog was touched as starting point

if no snapshot header was found. This can still be overriden by using
--since. Based on a patch by Felipe Sateler.

Closes: #511269

1 files changed, 6 insertions, 3 deletions

diff --git a/git-dch b/git-dch
index e8fd8a55..36acd18b 100755
--- a/git-dch
+++ b/git-dch
@@ -244,12 +244,15 @@ def shortlog_to_dch(repo, commits, options):
         add_changelog_entry(msg, author, email)
 
 
-def guess_snapshot_commit(cp):
+def guess_snapshot_commit(cp, repo):
     """guess the last commit documented in the changelog from the snapshot banner"""
     sr = re.search(snapshot_re, cp['Changes'])
     if sr:
         return sr.group('commit')
-
+    last = repo.commits(paths="debian/changelog", options=["-1"])
+    if last:
+        print "Changelog last touched at %s" % last
+        return last[0]
 
 
 def main(argv):
@@ -325,7 +328,7 @@ def main(argv):
         else:
             since = ''
             if options.auto:
-                since = guess_snapshot_commit(cp)
+                since = guess_snapshot_commit(cp, repo)
                 if since:
                     print "Continuing from commit '%s'" % since
                     found_snapshot_header = True