Please describe the problem:
From ubuntu upstream, seguso reports:
"When I right click on a ps.gz, the extract here option does not appear."


Steps to reproduce:
1. echo "123" > file.txt
2. gzip file.txt
3. cp file.txt.gz file.txt.ps.gz
4. Observe that when viewing these files in nautilus, one shows up as a "GZ"
archive using the appropriate icon, the other does not.
5. Right click on the file.txt.gz and notice that there is an extract here option.
6. Right click on the file.txt.ps.gz and notice that there is no "extract here"
option.


Actual results:


Expected results:


Does this happen every time?
Yes.

Other information:
It doesn't matter whether the file is an actual ps file or not.  This is done on
dapper with nautilus-2.13.91