Hello, I don't get an assert, but patch-2.5.9 refuses to patch CommonBuildDefines.opt. The file contains a mix of CRLF and LF line endings which patch-2.5.9 gets confused about. More recent versions of patch handle the line endings correctly.
If the problem still exists in patch-2.7.1, please provide the exact output of patch-2.7.1. Thanks, Andreas