mouseover color in *grep* buffer no on on some filenames

[Dan Jacobson]

Let's say we have emacs configured so that one sees colors during mouseover.
I see the color on the first four, but not the last three:

changelog.Debian.gz:14:  * Replaced dotlock alternative with lockmail.
changelog.Debian.gz:69:  * Fixed dotlock manual page link.
changelog.Debian.gz:125:  * Use alternatives for maildirmake and dotlock
changelog.Debian.gz:131:  * Remove dotlock from /usr/bin to avoid conflicts 
(closes: #54008)
changelog.gz:56:        * Replace dotlock with lockmail.
changelog.gz:173:       * Converted dotlock, mailbot, reformail, reformime man 
pages to
changelog.gz:505:* V0.54b - Changed auto-configuration logic for enabling 
dotlocks.

I did cd /usr/share/doc/maildrop/ (grep "zgrep -n -e dotlock *")
Emacs/21.2 .emacs = http://jidanni.org/comp/emacs.txt