Subject: using vc-annotate-find-revision-at-line for renamed/removed files

From: Dan Nicolaescu <[email-masked]>
Date: Mon, 21 Jun 2010 16:41:29 -0400

vc-annotate for git and mercurial shows the original file name for a
change, even if the file has been renamed meanwhile.
Using `vc-annotate-find-revision-at-line' on such a line in the annotate does not work

vc-annotate-find-revision-at-line calls vc-find-revision for a file
that does not exist anymore.
vc-find-revision in turn does a:
(vc-call find-revision file revision outbuf)
but given that the file does not exist anymore, no VC backend claims
the file, so the vc-call fails

vc-annotate-find-revision-at-line knows what VC backend it needs to
call, so it could pass it as an optional argument to vc-find-revision.