Should not attempt to create bucket by default on mkdir (fsspec#701)

Author: martindurant

gcsfs/core.py

@@ -878,7 +878,7 @@ async def _mkdir(
         acl="projectPrivate",
         default_acl="bucketOwnerFullControl",
         location=None,
-        create_parents=True,
+        create_parents=False,
         enable_versioning=False,
         enable_object_retention=False,
         iam_configuration=None,
@@ -931,10 +931,11 @@ async def _mkdir(
         if "/" in path and create_parents and await self._exists(bucket):
             # nothing to do
             return
-        if "/" in path and not create_parents:
+        if "/" in path:
             if await self._exists(bucket):
                 return
-            raise FileNotFoundError(bucket)
+            if not create_parents:
+                raise FileNotFoundError(bucket)
 
         json_data = {"name": bucket}
         location = location or self.default_location