Add a hook option that allows stdout to be printed when exit code is 0 (#695)

pre_commit/clientlib.py

@@ -68,6 +68,7 @@ MANIFEST_HOOK_DICT = schema.Map(
     schema.Optional('log_file', schema.check_string, ''),
     schema.Optional('minimum_pre_commit_version', schema.check_string, '0'),
     schema.Optional('stages', schema.check_array(schema.check_string), []),
+    schema.Optional('verbose', schema.check_bool, False),
 )
 MANIFEST_SCHEMA = schema.Array(MANIFEST_HOOK_DICT)
 

pre_commit/commands/run.py

@@ -130,7 +130,10 @@ def _run_single_hook(filenames, hook, repo, args, skips, cols):
 
     output.write_line(color.format_color(pass_fail, print_color, args.color))
 
-    if (stdout or stderr or file_modifications) and (retcode or args.verbose):
+    if (
+            (stdout or stderr or file_modifications) and
+            (retcode or args.verbose or hook['verbose'])
+    ):
         output.write_line('hookid: {}\n'.format(hook['id']))
 
         # Print a message if failing due to file modifications