sup-tweak-labels: sync back if specified

[kalbasit]

RE: #295

sup-tweak will only sync back if

1 - :sync_back_to_maildir is set to true (in ~/.sup/config.yml)
2 - sup-tweak was ran with the option --sync-back
3 - The modified email comes from a source with sync_back enabled (in ~/.sup/sources.yml)

[gauteh]

Thanks for the PR.

Actually; looking a bit more closely at the sync_back routines I saw that sync_back is guarded on each source anyway in Message::Location. Your code (and my original) will also not work quite as we expect since a Message will have many sources, m.source only gets the first location that is valid, so you are only checking the first valid source, while a call to m.sync_back will sync back to all the sources with sync_back enabled (message.rb:759).

Since a sync_back is guarded already for the global option (we can still keep the guard in -tweak-labels) and it is guarded per-source already, I think that the more appropriate solution is to rather have a --no-sync-back option - which will prevent any source from being sync'ed - whatever the global configuration and the per-source configuration.

[kalbasit]

Those were my thoughts exactly, to add a --no-sync-back, However I thought that this might change the behavior of it and people will start experiencing an unexpected behavior. If you're up for it I'll change my code around to make it work.

[gauteh]

Excerpts from Wael M. Nasreddine's message of 2014-04-30 20:01:17 +0200:

Those were my thoughts exactly, to add a --no-sync-back, However I thought that this might change the behavior of it and people will start experiencing an unexpected behavior. If you're up for it I'll change my code around to make it work.

that would be great! apparently not many people use tweak-back, it's
been broken for a while.

[kalbasit]

I changed it so the index never sync back and the message itself sync_back if it can.

[gauteh]

Merged. Thanks.