Please describe the problem:
Reported at https://bugs.launchpad.net/bugs/192330
Cannot extract multi-part zip archive files

Steps to reproduce:
1. Find a zip archive in multiple files (file.zip file.z01 file.z02 etc.)
2. Right-click on file.zip and select "Extract here"

Actual results:
warning [/home/username/Desktop/Fink.zip]: zipfile claims to be last disk of a multi-part archive;
  attempting to process anyway, assuming all parts have been concatenated
  together in order. Expect "errors" and warnings...true multi-part support
  doesn't exist yet (coming soon).
file #1: bad zipfile offset (local header sig): 4
file #2: bad zipfile offset (local header sig): 27969969
file #3: bad zipfile offset (lseek): 49012736

Expected results:
file-roller should concat the zip files together, fix the zip file and try to process it.

As explained in "man unzip":
"Multi-part archives are not yet supported, except in conjunction with zip. (All parts must be concatenated together in order, and then "zip -F" must be performed on the concatenated archive in order to "fix" it.) This will definitely be corrected in the next major release."
This should be fixed however, until the 'real' multi-part support arrives with the 6.0 release.

Does this happen every time?
Yes

Other information:
Original description:
"Ubuntu Gutsy gibbon 7.10 amd64
(I have installed p7zip p7zip-full rar unrar)
I tried to unzip multipart file archive (Fink.zip Fink.z01 Fink.z02 Fink.z03).

Right click -> extract here and it outputs this error:

warning [/home/username/Desktop/Fink.zip]: zipfile claims to be last disk of a multi-part archive;
  attempting to process anyway, assuming all parts have been concatenated
  together in order. Expect "errors" and warnings...true multi-part support
  doesn't exist yet (coming soon).
file #1: bad zipfile offset (local header sig): 4
file #2: bad zipfile offset (local header sig): 27969969
file #3: bad zipfile offset (lseek): 49012736

Then tried the command: 7za x Fink.zip
with this error:

7-Zip (A) 4.51 beta Copyright (c) 1999-2007 Igor Pavlov 2007-07-25
p7zip Version 4.51 (locale=en_US.UTF-8,Utf16=on,HugeFiles=on,2 CPUs)
Processing archive: Fink.zip
Error: Can not open file as archive

I even tried unrar / rar and they don't support the file. It looks like they can't handle multipart zip files.
The multipart files were extracted successfully in a Windows environment, using Winrar 3.71"