git_get_ref: Move to Dgit.pm and reimplement

Use
  git for-each-ref --format=%(objectname) [r]efs/whatever

This pattern won't match literally as a prefix because a ref name
cannot contain [, so it must match according to fnmatch.  whatever
cannot contain fnmatch metacharacters because they're not valid in ref
names.

This is a better idiom because it might directly look up the ref in
question (although currently it probably doesn't).

1 files changed, 0 insertions, 17 deletions

diff --git a/dgit b/dgit
index 1e348f3..42f9f45 100755
--- a/dgit
+++ b/dgit
@@ -667,23 +667,6 @@ sub parsechangelog {
     return $c;
 }
 
-sub git_get_ref ($) {
-    my ($refname) = @_;
-    my $got = cmdoutput_errok @git, qw(show-ref --), $refname;
-    if (!defined $got) {
-	$?==256 or fail "git show-ref failed (status $?)";
-	printdebug "ref $refname= [show-ref exited 1]\n";
-	return '';
-    }
-    if ($got =~ m/^(\w+) \Q$refname\E$/m) {
-	printdebug "ref $refname=$1\n";
-	return $1;
-    } else {
-	printdebug "ref $refname= [no match]\n";
-	return '';
-    }
-}
-
 sub must_getcwd () {
     my $d = getcwd();
     defined $d or fail "getcwd failed: $!";