bug#4982: rgrep can't deal with .gz files

[Juri Linkov]

> > Hmm, strange.  In http://thread.gmane.org/gmane.emacs.bugs/16956
> > you requested us to remove highlighting when there are additional
> > filters on the grep output.  So we changed `--color=always' into
> > `--color=auto' that broke the highlighting in zgrep output because
> > zgrep uses additional filters.

> Maybe zgrep is careful to distinguish filters on the input from
> filters on the output.  AFAICT zgrep only uses a filter on the input,
> so it should work.

IIUC, zgrep puts a sed filter on the grep output to replace
"(standard input)" strings with real file names.

-- 
Juri Linkov
http://www.jurta.org/emacs/