find_file_by_path doesn't take in account path relativity

When trying to find a file, find_file_by_path only matches the 'path' property with the file_ref under the group. If the path passed in the method is relative to the SOURCE_ROOT, and the path in the file_ref is relative to the group, it wouldn't find it.

Example:
I have two files: RoundView.h and RounView.m under the folder in the file system: myproject/classes/views/ .They are both in the group 'views' in the Xcode project, but the sourceTree are different:

RoundView.h path='classes/views/RoundView.h' sourceTree = SOURCE_ROOT
RoundView.m path='RoundView.m' sourceTree = ''

So I may know they are under 'classes/views/' but not how they where added to Xcode.