[PATCH 2/5] gnome-post-receive-email: Handle initial push

[Todd Zullinger <tmz pobox com>]

Commit fe7b408 (Don't show commits since the beginning of time for
branch creation) introduced a check which uses the parent of the first
commit we're interested in showing.  If this hook is enabled when the
initial push is made to the repository, that commit has no parent and
the call to git rev-list yields an error (and 128 return code).  This
prevents that by checking that the parent of first_detailed_commit is a
valid ref before using it.
---
 gnome-post-receive-email |   12 +++++++++---
 1 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/gnome-post-receive-email b/gnome-post-receive-email
index 577229f..2950832 100755
--- a/gnome-post-receive-email
+++ b/gnome-post-receive-email
@@ -236,9 +236,15 @@ class BranchChange(RefChange):
             # branch creation was processed first.
             #
             if len(detailed_commits) > 0:
-                first_detailed_commit = detailed_commits[-1]
-                self.added_commits = rev_list_commits(first_detailed_commit + "^.." + self.newrev)
-                self.added_commits.reverse()
+                # Verify parent of first detailed commit is valid. On initial push, it is not.
+                parent = detailed_commits[-1] + "^"
+                try:
+                    validref = git.rev_parse(parent, _quiet=True)
+                except CalledProcessError:
+                    self.added_commits = []
+                else:
+                    self.added_commits = rev_list_commits(parent + ".." + self.newrev)
+                    self.added_commits.reverse()
             else:
                 self.added_commits = []
             self.removed_commits = []
-- 
1.6.3.3