Retention: Align host filter with "backup"

[jkellerer]

Aligns the --host filter of "retention" (forget) with "backup" in restic (if host is not set, it defaults to os.Hostname() in restic, but forget has no default matching all hosts if unset)

After this change, when using retention in version 2 configs, all 3 filters path, tags and host are aligned with the backup section if not redefined.

Other changes:

• Auto enables after-backup: true if nothing was specified explicitly but keep-* is set
  (to avoid case like `backup` followed by `forget --prune` in a schedule #226).
• Fixes a problem with the tag copy from backup. Tags must be copied as single flag ("tag1,tag2,tag3,...") instead of multiple flags to match correctly
  (mentioned in Configuring a retention on a stdin profile applies the retention policy to the whole repository #225)

@creativeprojects : before I create tests, what do you think on this?

[creativeprojects]

before I create tests, what do you think on this?

Yes this is a good idea 👍🏻

I was also thinking we should fix the inconsistency of retention.after-backup and backup.check-after but that's out of the scope of this MR.

Sorry I'm very busy this week, and the next one as well. We're deploying a new project to production next week 😉

[codecov]

Codecov Report

Patch coverage: 96.83% and project coverage change: +0.09% 🎉

Comparison is base (347501d) 77.39% compared to head (3e0d095) 77.48%.
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #227      +/-   ##
==========================================
+ Coverage   77.39%   77.48%   +0.09%     
==========================================
  Files          93       93              
  Lines       10034    10074      +40     
==========================================
+ Hits         7765     7805      +40     
  Misses       2004     2004              
  Partials      265      265              

Flag	Coverage Δ
unittests	77.48% <96.83%> (+0.09%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
wrapper.go	85.50% <0.00%> (ø)
config/info_customizer.go	100.00% <100.00%> (ø)
config/profile.go	93.72% <100.00%> (+0.38%)	⬆️

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[jkellerer]

@creativeprojects , think the PR is ready for review now. What do you think?

[creativeprojects]

LGTM 😄

BTW we should keep track of all the subtle differences between v1 and v2 so we can make a exhaustive upgrade documentation

Thanks 😉

[jkellerer]

Guess we’ll need to review usages of config.Version when we document differences. This time it is in the reference at least 🙂