If I try to open an gzip file(test) which has no .gz file-extension I get an error.

I would expect that File-Roller checks the file-type of test like 'file' does it
$file test
test: gzip compressed data
or
$file -i test
test: application/x-gzip
and decompresses it.

If I try to open an gziped File which has no .gz extension File-Roller gives me an error message which says:
>test< konnte nicht geöffndet werden.
Archivtyp nicht unterstützt.

Note that if the file extension is ended by .tar, the error dissapear.
So, the error only appears with a non (.tar or .tar.gz) extension for the filename.

Other information:
ProblemType: Bug
Architecture: i386
Date: Wed Jul 16 02:38:14 2008
DistroRelease: Ubuntu 7.10
ExecutablePath: /usr/bin/file-roller
NonfreeKernelModules: fglrx
Package: file-roller 2.20.1-0ubuntu1
PackageArchitecture: i386
ProcCmdline: file-roller file:///home/atlanx/Desktop/test
ProcCwd: /home/atlanx
ProcEnviron:
 PATH=/home/atlanx/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: file-roller
Uname: Linux atlanx-laptop 2.6.22-15-generic #1 SMP Fri Jul 11 19:25:33 UTC 2008 i686 GNU/Linux

LaunchPad bug report: https://bugs.launchpad.net/ubuntu/+source/file-roller/+bug/248868