bug#11728: 24.1.50; vc-pull inconsistent behavior

[Sam Steingold <sds@gnu.org>]

In GNU Emacs 24.1.50.1 (x86_64-unknown-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2012-06-14 on t520sds
Bzr revision: 108611 sds@gnu.org-20120614195528-thu3is79zfv549gg
Windowing system distributor `The X.Org Foundation', version 11.0.11103000
Configured using:
 `configure '--with-wide-int''

when I do '+' in a vc-dir buffer, the behavior is inconsistent across
different backends;
1. svn: a bunch of messages in the *Messages* buffer/echo area, then the
changed files (if any) are present in the vc-dir buffer
2. bzr: a separate *vc-bzr: ...* buffer in compilation mode; changed
files are clickable there (but they do not appear in the vc-dir buffer)
3. hg, git: like bzr, but the new buffer is in fundamental mode and the
modified files are not clickable.

it would be nice if the interface were consistent, preferably in the svn
version to avoid creating a new buffer.

however, even the bzr version is much better than the hg/git one.
one simple was to unification is rename vc-bzr-error-regex-alist to
vc-bzr-error-regexp-alist for consistency with
compilation-error-regexp-alist and make it a vc backend symbol.
then call something based on

(with-current-buffer buf
	(vc-exec-after
	 `(progn
	    (let ((compilation-error-regexp-alist
		   vc-bzr-error-regexp-alist))
	      (compilation-mode))
	    (set (make-local-variable 'compilation-error-regexp-alist)
		 vc-bzr-error-regexp-alist))))

in vc.el, not each individual backend file.

-- 
Sam Steingold (http://sds.podval.org/) on Ubuntu 12.04 (precise) X 11.0.11103000
http://www.childpsy.net/ http://honestreporting.com http://memri.org
http://openvotingconsortium.org http://truepeace.org http://dhimmi.com
Sex is like air.  It's only a big deal if you can't get any.