gnulib-tool.py: Remove redundant backslashes from regexps. * pygnulib/GLTestDir.py (GLTestDir.execute): Don't backslash ']' when it is outside of a set. * pygnulib/GLImport.py (GLImport.__init__): Don't use a backslash when ']' is at the start of a '[...]' set. Don't backslash special characters in a '[...]' set since they have their meaning dropped. * pygnulib/main.py (main): Likewise.