When a diff contains a line starting with '--- ', diff2html.py
misinterprets it as being the header of a diff for a different file,
which apparently causes it to hang. This fix tries to work around the
problem by being a bit more selective about the format of the headers

It happened quite frequently to me that the paper stopped compiling
after the removal of the \usepackage{hyperref} from the main tex file.
Maybe it's just save to let it in.