treat *_test.py files as candidate test files

.vimrc

@@ -326,7 +326,7 @@ function! RunTestFile(...)
     endif
 
     " Run the tests for the previously-marked file.
-    let in_test_file = match(expand("%"), '\(.feature\|_spec.rb\)$') != -1
+    let in_test_file = match(expand("%"), '\(.feature\|_spec.rb\|_test.py\)$') != -1
     if in_test_file
         call SetTestFile()
     elseif !exists("t:grb_test_file")