master 46a2c19: Fix vc-annotate-show-log-revision-at-line

[Dmitry Gutov]

branch: master
commit 46a2c191f2cdda4144dfe7bfce064588f2b2f780
Author: Dmitry Gutov <dgutov@yandex.ru>
Commit: Dmitry Gutov <dgutov@yandex.ru>

    Fix vc-annotate-show-log-revision-at-line
    
    * lisp/vc/vc-annotate.el (vc-annotate-show-log-revision-at-line):
    Stop from being affected by 'vc-git-print-log-follow'.
    
    * lisp/vc/vc-git.el (vc-git-print-log-follow):
    Mention caveats in a comment.
---
 lisp/vc/vc-annotate.el | 3 +++
 lisp/vc/vc-git.el      | 8 ++++++++
 2 files changed, 11 insertions(+)

diff --git a/lisp/vc/vc-annotate.el b/lisp/vc/vc-annotate.el
index 82531f7..45bb177 100644
--- a/lisp/vc/vc-annotate.el
+++ b/lisp/vc/vc-annotate.el
@@ -545,6 +545,7 @@ Return a cons (REV . FILENAME)."
 
 (defvar log-view-vc-backend)
 (defvar log-view-vc-fileset)
+(defvar vc-git-print-log-follow)
 
 (defun vc-annotate-show-log-revision-at-line ()
   "Visit the log of the revision at line.
@@ -559,6 +560,8 @@ the file in question, search for the log entry required and 
move point."
          (message "Cannot extract revision number from the current line")
        (let ((backend vc-annotate-backend)
              (log-buf (get-buffer "*vc-change-log*"))
+              ;; No need to follow renames: we specify the historical file 
name.
+              vc-git-print-log-follow
              pos)
          (if (and
               log-buf
diff --git a/lisp/vc/vc-git.el b/lisp/vc/vc-git.el
index 8332600..eca8d54 100644
--- a/lisp/vc/vc-git.el
+++ b/lisp/vc/vc-git.el
@@ -1147,6 +1147,14 @@ This prompts for a branch to merge from."
 
 (autoload 'vc-setup-buffer "vc-dispatcher")
 
+;; It's a weird option due to how Git handles '--follow', and it can
+;; hide certain (usually merge) commits in the `vc-print-log' buffers.
+;;
+;; (setq vc-git-log-switches '("-m")) can fix that, but at the cost of
+;; duplicating many merge commits in the log.
+;;
+;; Long explanation here:
+;; 
https://stackoverflow.com/questions/46487476/git-log-follow-graph-skips-commits
 (defcustom vc-git-print-log-follow nil
   "If true, follow renames in Git logs for a single file."
   :type 'boolean