Add tests/test*.py to source distributions

Because most Python packages maintain tests in top-level directory
`tests/` instead of `test/`, add both to source distributions for
consistency.

Author: DimitriPapadopoulos

distutils/command/sdist.py

@@ -235,7 +235,7 @@ def add_defaults(self):
         """Add all the default files to self.filelist:
           - README or README.txt
           - setup.py
-          - test/test*.py
+          - tests/test*.py and test/test*.py
           - all pure Python modules mentioned in setup script
           - all files pointed by package_data (build_py)
           - all files defined in data_files.
@@ -293,7 +293,7 @@ def _add_defaults_standards(self):
                     self.warn("standard file '%s' not found" % fn)
 
     def _add_defaults_optional(self):
-        optional = ['test/test*.py', 'setup.cfg']
+        optional = ['tests/test*.py', 'test/test*.py', 'setup.cfg']
         for pattern in optional:
             files = filter(os.path.isfile, glob(pattern))
             self.filelist.extend(files)