interfaces_file: filter by address_familiy when updating method (#7612)
* When updating method, check address_family if provided.
* Also test modifying 'method' without address_family filter.
(cherry picked from commit 5adb7ab948)
Co-authored-by: Felix Fontein <felix@fontein.de>
* pythonific!! no camel cases, bitte
* simplified iface attributes parsing
* some improvements, passing tests
* simplified set_interface_option()
* further simplifications
* remove unreachable stmt
* pythonified a file open
* added changelog fragment
* adjustment per PR
* PR: fixed the auto- case
* PR: added testcase and chglog frag for the misleading change report
* extra line removed
* integration is not destructive