When gcc path is set to r"$nimrod\dist\mingw\bin", the compiler gives
an error:
Error : unhandled exception : invalid format string [Value Error], but
works correctly with gcc.path set to r"$nim\dist\mingw\bin". I think
this issue was caused due to the name change from nimrod to nim , but
the name change was not replicated in the config file.
Considering that alternatives to the Apple compiler versions of xcode like GCC 4.9 (as installed by Homebrew) error out because it is an unknown parameter. Modern Xcode's clang + gcc do not seem to need this anymore.
I think it is ok to remove because developer with old xcode are rare and can easily add this to their systems if needed.