bug#21535: 25.0.50; vc-follow-symlinks=ask is ineffective for directory links

[Johan Bockgård]

When `vc-follow-symlinks' is `ask' (the default) Emacs follows links for
files under version control, but fails to ask before doing so when any
parent directory is a symlink.

E.g.
/x/y/link  (asks)
/x/link/z  (doesn't ask)

The following commit changed two occurrences of `file-chase-links' to
`buffer-file-truename' in vc-hooks.el. A third occurrence of
file-chase-links was left alone however, which fools the querying logic
for files where the directory part of the name contains symlinks.


commit 33f95a82e97cac000a98dc5b1100ad7a095e12d3
Author: Stefan Monnier <monnier@iro.umontreal.ca>
Date:   Sat Nov 22 05:23:42 2008 +0000

    (vc-follow-link, vc-find-file-hook):
    Use buffer-file-truename to handle symlinks in any part of the filename.