According to documentation and the code, the following behavior is expected:
ipv6 = no
AF_INET is used
ipv6 = yes
AF_INET6 is used
ipv6 undefined
AF_UNDEF is used
Unfortunately the code parsing the "ipv6" configuration option was
returning "False" rather than "None" when failing to locate the option,
making it impossible to detect whether "ipv6" isn't set or if it was set
to "false" and leading offlineimap to use AF_INET for the connection.
This fixes the use of offlineimap on hosts that occasionaly are
connected to IPv6-only networks.
Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Signed-off-by: Nicolas Sebrecht <nicolas.s-dev@laposte.net>
e3bbf75feb