Improve vc-bzr-working-revision for lightweight checkouts

* lisp/vc/vc-bzr.el (vc-bzr-working-revision): For lightweight local
checkouts, check the parent dirstate matches the branch.
Add "--tree" to "bzr revno" arguments.  Don't try to shorten the
empty string.

1 files changed, 10 insertions, 4 deletions

diff --git a/lisp/vc/vc-bzr.el b/lisp/vc/vc-bzr.el
index c0dafda57b..1eb33776f6 100644
--- a/lisp/vc/vc-bzr.el
+++ b/lisp/vc/vc-bzr.el
@@ -534,7 +534,9 @@ in the branch repository (or whose status not be determined)."
 			 ;; FIXME: maybe it's overkill to check if both these
 			 ;; files exist.
 			 (and (file-exists-p branch-format-file)
-			      (file-exists-p lastrev-file)))))
+			      (file-exists-p lastrev-file)
+			      (equal (emacs-bzr-version-dirstate l-c-parent-dir)
+				     (emacs-bzr-version-dirstate rootdir))))))
 		 t)))
         (with-temp-buffer
           (insert-file-contents branch-format-file)
@@ -553,13 +555,17 @@ in the branch repository (or whose status not be determined)."
             (insert-file-contents lastrev-file)
             (when (re-search-forward "[0-9]+" nil t)
 	      (buffer-substring (match-beginning 0) (match-end 0))))))
-      ;; fallback to calling "bzr revno"
+      ;; Fallback to calling "bzr revno --tree".
+      ;; The "--tree" matters for lightweight checkouts not on the same
+      ;; revision as the parent.
       (let* ((result (vc-bzr-command-discarding-stderr
-                      vc-bzr-program "revno" (file-relative-name file)))
+                      vc-bzr-program "revno" "--tree"
+                      (file-relative-name file)))
              (exitcode (car result))
              (output (cdr result)))
         (cond
-         ((eq exitcode 0) (substring output 0 -1))
+         ((and (eq exitcode 0) (not (zerop (length output))))
+          (substring output 0 -1))
          (t nil))))))
 
 (defun vc-bzr-create-repo ()