[1.9.x] Fixed #26016 -- Restored contrib.auth hashers compatibility with py-bcrypt.

Reverted "Explicitly passed rounds as rounds to bcrypt.gensalt()"

This reverts commit 23529fb19594ffcc6ba6d716356b828157200288.

Backport of f0ad641628a3ddc4e1c208e481b9cd0e9304dc3d from master

django/contrib/auth/hashers.py

@@ -286,7 +286,7 @@ class BCryptSHA256PasswordHasher(BasePasswordHasher):
 
     def salt(self):
         bcrypt = self._load_library()
-        return bcrypt.gensalt(rounds=self.rounds)
+        return bcrypt.gensalt(self.rounds)
 
     def encode(self, password, salt):
         bcrypt = self._load_library()

docs/releases/1.9.1.txt

@@ -76,3 +76,6 @@ Bugfixes
 
 * Made ``loaddata`` skip disabling and enabling database constraints when it
   doesn't load any fixtures (:ticket:`23372`).
+
+* Restored ``contrib.auth`` hashers compatibility with py-bcrypt
+  (:ticket:`26016`).