bug#63949: 30.0.50; `vc-print-log´ does not erase buffer when called from *vc-change-log* buffer, at least for CVS logs

[Dmitry Gutov <dmitry@gutov.dev>]

(Please keep the bug address in Cc).

On 18/06/2023 16:21, Jens Schmidt wrote:
> On 2023-06-18  14:00, Dmitry Gutov wrote:
> 
>> Could you test the patch I showed?
> 
> Will do, pls just give me some time here...

Thanks. If we can verify that the part broken by the bisected revision, 
is fixed here, we could push that to Emacs 29 and then clean up for 
Emacs 30 more thoroughly.

In the meantime, here's the updated patch. The previous one discarded 
the return value :(

diff --git a/lisp/vc/vc.el b/lisp/vc/vc.el
index 91d3f6f70d3..c8b2b3ac11d 100644
--- a/lisp/vc/vc.el
+++ b/lisp/vc/vc.el
@@ -1121,10 +1121,15 @@ vc-deduce-fileset
  the returned list.

  BEWARE: this function may change the current buffer."
-  (with-current-buffer (or (buffer-base-buffer) (current-buffer))
-    (vc-deduce-fileset-1 not-state-changing
-                         allow-unregistered
-                         state-model-only-files)))
+  (let (new-buf res)
+    (with-current-buffer (or (buffer-base-buffer) (current-buffer))
+      (setq res
+            (vc-deduce-fileset-1 not-state-changing
+                                 allow-unregistered
+                                 state-model-only-files))
+      (setq new-buf (current-buffer)))
+    (set-buffer new-buf)
+    res))

  (defun vc-deduce-fileset-1 (not-state-changing
                              allow-unregistered