bug#68364: Print log buttons fail with vc-log-mergebase

[Juri Linkov <juri@linkov.net>]

>> Buttons to show more log entries is a nice feature,
>> but after the recent change this doesn't work with
>> 'C-x v M L' (vc-log-mergebase):
>>    Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p
>> "branch-2")
>>      vc-print-log-setup-buttons("branch-1" t "branch-2" nil)
>> Probably it requires a special handling for 'C-x v M L'.
>
> Does this help?
>
> Looks like the description of the LIMIT argument wasn't updated in the
> vc-print-log-internal's docstring, when it started to be a string
> sometimes.

The description of the LIMIT argument in vc-print-log-internal looks strange:

  "Show up to LIMIT entries (non-nil means unlimited)."

Maybe it should be "(nil means unlimited)"?

> diff --git a/lisp/vc/vc.el b/lisp/vc/vc.el
> index b8cc44fc3dc..7d5a5486250 100644
> --- a/lisp/vc/vc.el
> +++ b/lisp/vc/vc.el
> @@ -2711,7 +2711,7 @@ vc-print-log-setup-buttons
>    ;; In either case only one revision is wanted, no buttons.
>    (when (and limit (not (eq 'limit-unsupported pl-return))
>               (not (and is-start-revision
> -                       (= limit 1))))
> +                       (eql limit 1))))
>      (let ((entries 0))
>        (goto-char (point-min))
>        (while (re-search-forward log-view-message-re nil t)

Sorry, still fails on another line:

      (if (< entries limit)

But this works:

diff --git a/lisp/vc/vc.el b/lisp/vc/vc.el
index b8cc44fc3dc..d284b19fcf0 100644
--- a/lisp/vc/vc.el
+++ b/lisp/vc/vc.el
@@ -2709,7 +2709,8 @@ vc-print-log-setup-buttons
   ;; LIMIT=1 is set by vc-annotate-show-log-revision-at-line
   ;; or by vc-print-root-log with current-prefix-arg=1.
   ;; In either case only one revision is wanted, no buttons.
-  (when (and limit (not (eq 'limit-unsupported pl-return))
+  (when (and limit (not (stringp limit))
+             (not (eq 'limit-unsupported pl-return))
              (not (and is-start-revision
                        (= limit 1))))
     (let ((entries 0))