Using a git snapshot of the script, i found today the following traceback :
{{{
State Changed: end
Build completed ok
Downloading (Source0): http://downloads.sourceforge.net/scantailor/scantailor-0.9.11.1.tar.gz
No upstream for (Source1): scantailor.desktop
The source scantailor.desktop in the srpm can not be retrieved. This is a corner case not supported yet.
Running checks and generate report

Cannot find source: scantailor-0.9.11.1.tar.gz
Checking source md5 : /home/misc/checkout/git/FedoraReview/src/821732/scantailor-0.9.11.1.tar.gz
Trying to unpack non-existing source: scantailor-0.9.11.1.tar.gz
Cannot extract local source: /home/misc/checkout/git/FedoraReview/src/821732/scantailor-0.9.11.1.tar.gz
None <type 'NoneType'>
Traceback (most recent call last):
File "./fedora-review", line 234, in <module>
review.run()
File "./fedora-review", line 224, in run
self.__do_report()
File "./fedora-review", line 125, in __do_report
self.__do_report_local(self.args.workdir)
File "./fedora-review", line 134, in __do_report_local
self.__run_checks(files_spec[0], files_srpm[0])
File "./fedora-review", line 187, in __run_checks
self.checks.run_checks(output=output)
File "/home/misc/checkout/git/FedoraReview/src/FedoraReview/misc.py", line 137, in run_checks
test.run()
File "/home/misc/checkout/git/FedoraReview/src/FedoraReview/checks/generic.py", line 393, in run
f.write(diff)
TypeError: expected a character buffer object
}}}

Likely caused by a spec who was out of sync with the srpm ( see last comment on the bug ).

Here is a patch to prevent the traceback.