This is a very short permissive license found in the perl module Time::ParseDate. The request to "feed useful changes back" is interpreted as a polite request, not a requirement. It is Free and GPL compatible.
Copyright (C) 1996-2010 David Muir Sharnoff. Copyright (C) 2011 Google, Inc. License hereby granted for anyone to use, modify or redistribute this module at their own risk. Please feed useful changes back to firstname.lastname@example.org.