Android: SMB credentials not remembered

When supplying a login for SMB, the dialog has the option "remember password". Even when ticking this option, when browsing a protected SMB share without anonymous access, I am prompted for credentials at every folder, but the username and password are not pre-filled. Built-in file browser is therefore effectively unusable for SMB shares without anonymous access. (No, enabling anonymous access is not a solution.)

To be clear:

1. Browse to a SMB share without anonymous access.
2. Login prompt appears. Enter credentials and tick "Remember password".
3. Login succeeds. Browse to a subfolder. Expected: Subfolder contents appear.

Actual: Login prompt appears again.

Might be related to #17858 (closed)

Reproduced for 2.0.6 - Android 7.1 on Nexus 9 and 5.1.1 on Xperia Z.