The patch doesn't apply cleanly because the following hunk is already present on master:

try:
    import httplib
except ImportError:
    import http.client as httplib

Could you rebase the commit onto master?

This is missing the import stuff, isn't it?

res.append(c)

Just remove chr()
c is single character of a string, but not an integer value of a character.
I could see via grep, decode(s) is used with folders in modules used for imap

Dropped the need for an email address, fixed spacing

• Add an option to disable LDAP backend

Required with the new docker-networking setup.

Addressed comments, added redis check.

A fixed version is already in Kolab:16:Testing; it should hit the Kolab:16 repository soon.

The workaround to install roundcubemail 1.5.2 did not uninstall/remove roundcubemail-plugin-kolab-delegation.
Now I cannot install roundcubemail 1.5.3 because I get follwoing error...