+*git_default_branchname = $opt_o ? *old_style_branchname : *tree_dirname;
+
+# retrieve default archive, since $branch_name_map keys might not include it
+sub get_default_archive {
+ if (!defined $default_archive) {
+ $default_archive = safe_pipe_capture($TLA,'my-default-archive');
+ chomp $default_archive;
+ }
+ return $default_archive;
+}
+
+sub git_branchname {
+ my $revision = shift;
+ my $name = extract_versionname($revision);
+
+ if (exists $branch_name_map{$name}) {
+ return $branch_name_map{$name};
+
+ } elsif ($name =~ m#^([^/]*)/(.*)$#
+ && $1 eq get_default_archive()
+ && exists $branch_name_map{$2}) {
+ # the names given in the command-line lacked the archive.
+ return $branch_name_map{$2};
+
+ } else {
+ return git_default_branchname($revision);
+ }
+}