Improve handling of the first Git revision

* lisp/vc/log-view.el (log-view-toggle-entry-display): When
there's no next entry, delete until the end of the buffer.
(log-view-end-of-defun-1): Stop at eob.

* lisp/vc/vc-annotate.el
(vc-annotate-show-diff-revision-at-line-internal): Don't give up
when previous-revision is nil.

* lisp/vc/vc-git.el (vc-git-expanded-log-entry): End the arguments
with `--' to avoid ambiguity.
(vc-git-annotate-extract-revision-at-line): Exclude `^' from the
returned revision string.
(vc-git-annotate-time): Expect `^' before the first revision.

* lisp/vc/vc-git.el (vc-git-diff): Diff against an empty tree if
REV1 is nil, and REV2 is not.

* lisp/vc/vc.el: Update the description of the `diff' function.

1 files changed, 2 insertions, 1 deletions

diff --git a/lisp/vc/vc.el b/lisp/vc/vc.el
index d5d0abe6517..1bd04e13430 100644
--- a/lisp/vc/vc.el
+++ b/lisp/vc/vc.el
@@ -367,7 +367,8 @@
 ;;   BUFFER is nil.  If ASYNC is non-nil, run asynchronously.  If REV1
 ;;   and REV2 are non-nil, report differences from REV1 to REV2.  If
 ;;   REV1 is nil, use the working revision (as found in the
-;;   repository) as the older revision; if REV2 is nil, use the
+;;   repository) as the older revision if REV2 is nil as well;
+;;   otherwise, diff against an empty tree.  If REV2 is nil, use the
 ;;   current working-copy contents as the newer revision.  This
 ;;   function should pass the value of (vc-switches BACKEND 'diff) to
 ;;   the backend command.  It should return a status of either 0 (no