+ my $new_upstream = shift @ARGV;
+ if (!defined $new_upstream) {
+ my @tried;
+ # todo: at some point maybe use git-deborig to do this
+ foreach my $tagpfx ('', 'v', 'upstream/') {
+ my $tag = $tagpfx.(dep14_version_mangle $new_upstream_version);
+ $new_upstream = git_get_ref "refs/tags/$tag";
+ last if length $new_upstream;
+ push @tried, $tag;
+ }
+ if (!length $new_upstream) {
+ fail "Could not determine appropriate upstream commitish.\n".
+ " (Tried these tags: @tried)\n".
+ " Check version, and specify upstream commitish explicitly.";
+ }
+ }
+ $new_upstream = git_rev_parse $new_upstream;