dgit: Do not fail when run with detached HEAD. Closes:#853022.

Specifically:

* Pass -q to git-symbolic-ref.  That means that it doesn't print
  an error message when HEAD is not a symbolic ref (ie, a
  detached head), and it means that the exit status is then 1
  rather than 128.

* If the return value from cmdoutput_errok is undef, check $? (which
  is the exit status <<8) and then simply pass on the undef.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

1 files changed, 5 insertions, 1 deletions

diff --git a/dgit b/dgit
index f1f9332..724dba1 100755
--- a/dgit
+++ b/dgit
@@ -4435,8 +4435,12 @@ sub cmd_clone {
 }
 
 sub branchsuite () {
-    my @cmd = (@git, qw(symbolic-ref HEAD));
+    my @cmd = (@git, qw(symbolic-ref -q HEAD));
     my $branch = cmdoutput_errok @cmd;
+    if (!defined $branch) {
+	$?==256 or failedcmd @cmd;
+	return undef;
+    }
     if ($branch =~ m#$lbranch_re#o) {
 	return $1;
     } else {