Bug#759912: mb2md: broken path handling

[Dafydd Harries]

Package: mb2md
Version: 3.20-6
Severity: normal

Using Debian mb2md:

    $ mb2md -s /home/daf/notmuch.mbox -d /home/daf/mail/notmuch
    Converting /home/daf/notmuch.mbox to maildir: /home/daf/mail/notmuch
    Source Mbox is /home/daf/notmuch.mbox
    Target Maildir is /home/daf/mail/notmuch 
    Fatal: unable to open input mailbox file: /home/daf//home/daf/notmuch.mbox ! 

Using unpatched mb2md (from `debcheckout mb2md`):

    $ perl mb2md-3.20.pl -s /home/daf/notmuch.mbox -d /home/daf/mail/notmuch 
    /home/daf/notmuch.mbox
    /home/daf/notmuch.mbox
    Converting /home/daf/notmuch.mbox to maildir: /home/daf/mail/notmuch
    Source Mbox is /home/daf/notmuch.mbox
    Target Maildir is /home/daf/mail/notmuch 
    18951 messages.

This seems to be caused by debian/patches/fix-path-expansion.patch,
specifically this hunk:

    @@ -754,6 +755,7 @@
             # Change to the target mailbox directory.
     
             chdir "$maildir" ;
    +        $mbox = "$pwd/$mbox";
     
                        # Converts a Mbox to multiple files
                         # in a Maildir.