Spaces in password cause mail fetching to fail

If you have spaces in your email account password for bounce processing, fetching data via IMAP simply fails. This is not good. But seems like it should be a simple fix, some string quoting needed?

The Civi job log reports the IMAP server's error as:

"The IMAP server did not accept the username and/or password: A0001 BAD Error in IMAP command received by server."

but what we see in the server log is that Civi submitted no username at all (blank string inside the <>):

"dovecot: imap-login: Aborted login (no auth attempts in 0 secs): user=<>"