Split out building a debian version from an upstream commit

based on a patch by Daniel Dehennin

Needed for #672954, #646684, #669171

2 files changed, 28 insertions, 10 deletions

diff --git a/gbp/deb/git.py b/gbp/deb/git.py
index c9004ef..c7b6e77 100644
--- a/gbp/deb/git.py
+++ b/gbp/deb/git.py
@@ -62,6 +62,28 @@ class DebianGitRepository(GitRepository):
                     return None
         return None
 
+    def debian_version_from_upstream(self, upstream_tag_format, commit='HEAD',
+                                     epoch=None):
+        """
+        Build the Debian version that a package based on upstream commit
+        I{commit} would carry taking into account a possible epoch.
+
+        @param upstream_tag_format; the tag format on the upstream branch
+        @type upstream_tag_format; C{str}
+        @param commit: the commit to search for the latest upstream version
+        @param epoch: an epoch to use
+        @returns: a new debian version
+        @raises: L{GitRepositoryError} if no upstream tag was found
+        """
+        pattern = upstream_tag_format % dict(version='*')
+        tag = self.find_tag(commit, pattern=pattern)
+        version = self.tag_to_version(tag, upstream_tag_format)
+
+        version += "-1"
+        if epoch:
+            version = "%s:%s" % (epoch, version)
+        return version
+
     @staticmethod
     def _build_legacy_tag(format, version):
         """
diff --git a/gbp/scripts/dch.py b/gbp/scripts/dch.py
index f6bcfb1..86c0547 100644
--- a/gbp/scripts/dch.py
+++ b/gbp/scripts/dch.py
@@ -105,18 +105,14 @@ def guess_version_from_upstream(repo, upstream_tag_format, cp):
     """
     Guess the version based on the latest version on the upstream branch
     """
-    pattern = upstream_tag_format % dict(version='*')
     try:
-        tag = repo.find_tag('HEAD', pattern=pattern)
-        version = repo.tag_to_version(tag, upstream_tag_format)
-        if version:
-            gbp.log.debug("Found upstream version %s." % version)
-            if cp.has_epoch():
-                version = "%s:%s" % (cp.epoch, version)
-            if compare_versions(version, cp.version) > 0:
-                return "%s-1" % version
+        version = repo.debian_version_from_upstream(upstream_tag_format,
+                                                    epoch=cp.epoch)
+        gbp.log.debug("Found upstream version %s." % version)
+        if compare_versions(version, cp.version) > 0:
+            return version
     except GitRepositoryError:
-        gbp.log.debug("No tag found matching pattern %s." % pattern)
+        gbp.log.debug("No upstream tag found")
     return None