I created an image and a mdwn with an ampersand in the filename.
This gaves me some error messages.
I renamed the files and committed.

Even now, I still get the following error messages:

    Use of uninitialized value in substitution (s///) at /usr/lib64/perl5/vendor_perl/5.8.8/IkiWiki.pm line 764.
    Use of uninitialized value in substitution (s///) at /usr/lib64/perl5/vendor_perl/5.8.8/IkiWiki.pm line 768.
    Use of uninitialized value in concatenation (.) or string at /usr/lib64/perl5/vendor_perl/5.8.8/IkiWiki.pm line 773.
    Use of uninitialized value in concatenation (.) or string at /usr/lib64/perl5/vendor_perl/5.8.8/IkiWiki.pm line 773.
    Use of uninitialized value in concatenation (.) or string at /usr/lib64/perl5/vendor_perl/5.8.8/IkiWiki.pm line 773.
    Use of uninitialized value in concatenation (.) or string at /usr/lib64/perl5/vendor_perl/5.8.8/IkiWiki.pm line 773.