fix(ref): treat X#N as a reference only when X names a repository

Signed-off-by: bircni <bircni@icloud.com>

internal/app/ref.go

@@ -55,6 +55,10 @@ func parseRef(raw string, kind refKind) (ref, error) {
 	if !hashed {
 		repo, value = "", raw
 	}
+	// Only a repository before # makes a reference, so a branch such as fix#12 stays a branch.
+	if repo != "" && !repositoryLike(repo) {
+		return ref{}, errNotRef
+	}
 	n, err := strconv.ParseInt(value, 10, 64)
 	if err != nil && !hashed {
 		return ref{}, errNotRef
@@ -65,6 +69,12 @@ func parseRef(raw string, kind refKind) (ref, error) {
 	return ref{Number: n, Repo: repo}, nil
 }
 
+// repositoryLike reports whether raw has the form OWNER/REPO or HOST/OWNER/REPO.
+func repositoryLike(raw string) bool {
+	pieces := strings.Split(raw, "/")
+	return len(pieces) >= 2 && settings.ValidSlug(strings.Join(pieces[len(pieces)-2:], "/"))
+}
+
 func parseRefURL(raw string, kind refKind) (ref, error) {
 	invalid := clierr.Wrap(clierr.Usage, fmt.Errorf("%q is not %s URL; use %s", raw, kind.article(), kind.forms()))
 	u, err := url.Parse(raw)