result when the user doesn't want to write to the file.
(auth-source-netrc-search): Expect a synthetic result and proceed
accordingly.
+ (auth-source-cache-expiry): New variable to override
+ `password-cache-expiry'.
+ (auth-source-remember): Use it.
* nnimap.el (nnimap-credentials): Remove the `inhibit-create'
parameter. Create entry if necessary by using :create t.