bug#6465: Error during redisplay: (error No match 4 in highlight (4 font-lock-warning-face))

[Dan Nicolaescu]

When using C-x v v to check something in, there's a lot of messages
like this in the *Messages* buffer:

Error during redisplay: (error No match 4 in highlight (4 
font-lock-warning-face)) [3 times]

Probably the cause is this change to `log-edit-font-lock-keywords':

2010-04-21  Stefan Monnier  <monnier@iro.umontreal.ca>

            Make the log-edit comments use RFC822 format throughout.

            * vc.el (vc-checkin, vc-modify-change-comment):
            Adjust to new vc-start/finish-logentry.
            (vc-find-conflicted-file): New command.
            (vc-transfer-file): Adjust to new vc-checkin.
            (vc-next-action): Improve scoping.

            * vc-hg.el (vc-hg-log-edit-mode): Remove.
            (vc-hg-checkin): Remove extra arg.  Use log-edit-extract-headers.

            * vc-git.el (vc-git-log-edit-mode): Remove.
            (vc-git-checkin): Remove extra arg.  Use log-edit-extract-headers.
            (vc-git-commits-coding-system): Rename from 
git-commits-coding-system.

            * vc-dispatcher.el (vc-log-edit): Shorten names for 
log-edit-show-files.
            (vc-start-logentry): Remove argument `extra'.
            (vc-finish-logentry): Remove extra args.

            * vc-bzr.el (vc-bzr-log-edit-mode): Remove.
            (vc-bzr-checkin): Remove extra arg.  Use log-edit-extract-headers.
            (vc-bzr-conflicted-files): New function.

            * log-edit.el (log-edit-extra-flags)
            (log-edit-before-checkin-process): Remove.
            (log-edit-summary, log-edit-header, log-edit-unknown-header): New 
faces.
            (log-edit-headers-alist): New var.
            (log-edit-header-contents-regexp): New const.
            (log-edit-match-to-eoh): New function.
            (log-edit-font-lock-keywords): Use them.
            (log-edit): Insert a "Summary:" header as default.
            (log-edit-mode): Mark font-lock rules as case-insensitive.
            (log-edit-done): Cleanup headers.
            (log-view-process-buffer): Remove.
            (log-edit-extract-headers): New function to replace it.