From: Juri Linkov <juri@linkov.net>
Date: Wed, 10 Nov 2021 18:41:19 +0000 (+0200)
Subject: * lisp/vc/vc-git.el (vc-git-mergebase): More meaningful error message.
X-Git-Tag: emacs-28.0.90~87
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=2963de6540a1dc57399eaf530d8e12c794137a84;p=emacs.git

* lisp/vc/vc-git.el (vc-git-mergebase): More meaningful error message.

Display a readable error message instead of signaling an error on nil value.
---

diff --git a/lisp/vc/vc-git.el b/lisp/vc/vc-git.el
index 3f89fad2351..2d35061b269 100644
--- a/lisp/vc/vc-git.el
+++ b/lisp/vc/vc-git.el
@@ -1256,7 +1256,10 @@ log entries."
 
 (defun vc-git-mergebase (rev1 &optional rev2)
   (unless rev2 (setq rev2 "HEAD"))
-  (string-trim-right (vc-git--run-command-string nil "merge-base" rev1 rev2)))
+  (let ((base (vc-git--run-command-string nil "merge-base" rev1 rev2)))
+    (if base
+        (string-trim-right base)
+      (error "No common ancestor for merge base"))))
 
 (defvar log-view-message-re)
 (defvar log-view-file-re)