dgit: Avoid crash if branch_is_gdr finds an origin commit

Closes: #910687.
Reported-by: Mattia Rizzolo <mattia@debian.org>
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/dgit b/dgit
index 4cc568457a8305b83dfd83024c909d0dd19654fb..19b9eb2c733954506716cda110e94d0ad0d57831 100755 (executable)
--- a/dgit
+++ b/dgit
@@ -379,6 +379,10 @@ sub branch_is_gdr ($) {
            printdebug "branch_is_gdr  $walk ?-octopus NO\n";
            return 0;
        }
            printdebug "branch_is_gdr  $walk ?-octopus NO\n";
            return 0;
        }

+       if (!@parents) {
+           printdebug "branch_is_gdr  $walk origin\n";
+           return 0;
+       }

        if ($get_patches->($walk) ne $tip_patches) {
            # Our parent added, removed, or edited patches, and wasn't
            # a gdr make-patches commit.  gdr make-patches probably
        if ($get_patches->($walk) ne $tip_patches) {
            # Our parent added, removed, or edited patches, and wasn't
            # a gdr make-patches commit.  gdr make-patches probably