Comment # 2 on bug 1179023 from Jean Delvare

So here is what happens. "quilt setup" calls rpmbuild to process the spec file,
and intercepts all the calls to tar, patch and the like to setup the working
directory and generate the series file.

It turns out that, when there is a symbolic link on the way to the patch files
(as in your second example), rpmbuild apparently resolves the link before
passing the result to the patch command. So when quilt gets the information,
it's already too late, we have lost track of the original path of the patch
file.

"quilt setup" gets the patch file name as an absolute path in both cases. It
would normally strip the prefix at this point, so that the patch file name is a
relative path in the series file (typically just the name of the file, in the
simple case, as in your first example). Here it fails because the prefix of the
patch file name and the prefix of the working directory do not match.