Fix #11491. When dbm.open was called with a file which already exists and

the "flag" argument is "n", dbm.error was being raised. As documented,
dbm.open(...,flag='n') will now "Always create a new, empty database,
open for reading and writing", regardless of a previous file existing.

1 files changed, 3 insertions, 3 deletions

diff --git a/Lib/dbm/__init__.py b/Lib/dbm/__init__.py
index b2a254a..6e890f3 100644
--- a/Lib/dbm/__init__.py
+++ b/Lib/dbm/__init__.py
@@ -67,10 +67,10 @@ def open(file, flag = 'r', mode = 0o666):
         if not _defaultmod:
             raise ImportError("no dbm clone found; tried %s" % _names)
 
-    # guess the type of an existing database
-    result = whichdb(file)
+    # guess the type of an existing database, if not creating a new one
+    result = whichdb(file) if 'n' not in flag else None
     if result is None:
-        # db doesn't exist
+        # db doesn't exist or 'n' flag was specified to create a new db
         if 'c' in flag or 'n' in flag:
             # file doesn't exist and the new flag was used so use default type
             mod = _defaultmod