Bug: empty prefix value in userdb lookup defaults to "yes"?

[Dan Malm]

Hi,

I'm trying to migrate some users into our system from another one that
also run dovecot but with different prefix and separator settings than
we do.

I've setup userdb to return these values for a test user to match the
other systems separator/prefix setup:
{
  "home": "/customers/b/5/3/cdeadbeef/mail/m0123456789abcdef/",
  "namespace/inbox/separator": "/",
  "uid": 10000001,
  "namespace/inbox/prefix": "",
  "gid": 10000001
}

But the empty value for prefix seems to get converted to some default
value of "yes" as when I log in with that user dovecot throws this error:

Error: namespace configuration error: list=yes requires prefix=yes to
end with separator /

Dovecot version: 2.3.13
OS: Ubuntu 20.04.2

-- 
BR/Mvh. Dan Malm, Systems Engineer, One.com