Because, if you are not using sync_back on all your sources you have the
possibility to specify whether -tweak-labels should sync_back for the
sources you specify. Currently -tweak-labels are ignoring per-source
syncback settings.. (I think).

Also, in case you want to modify labels without modifying the message.
In particular in the case where you are using the maildir-root branch
and don't want to move/delete any messages, or where the source may be
out of sync for some reason.

But yeah, it's not absolutely ideal.

Excerpts from Wael M. Nasreddine's message of 2014-04-29 21:03:57 +0200:
> > @@ -51,6 +52,7 @@ EOS
> >    opt :very_verbose, "Print message names and subjects as they're processed."
> >    opt :all_sources, "Scan over all sources.", :short => :none
> >    opt :dry_run, "Don't actually modify the index. Probably only useful with --verbose.", :short => "-n"
> > +  opt :sync_back, "Sync back maildir flags if enabled globally (important: source specific sync_back changes will be _ignored_.)"
> 
> Why not use this option rather than this **AND** the global setting in the config file?
> 
> ```
> opt :sync_back, "Sync back maildir"
> ```
> 
> ---
> Reply to this email directly or view it on GitHub:
> https://github.com/sup-heliotrope/sup/pull/295/files#r12111005