removedir(force=True): guard against new files being created in the target dir

fs/osfs.py

@@ -116,7 +116,13 @@ class OSFS(FS):
         #  Don't remove the root directory of this FS
         if path in ("","/"):
             return
-        os.rmdir(sys_path)
+        try:
+            os.rmdir(sys_path)
+        except OSError, e:
+            if e.errno != errno.ENOTEMPTY or not force:
+                raise
+            #  Someone has created files in here in the meantime, try again.
+            self.removedir(path,recursive=False,force=True)
         #  Using os.removedirs() for this can result in dirs being
         #  removed outside the root of this FS, so we recurse manually.
         if recursive: