Only update mirror last update after successful sync

[cez81]

Fix #2535

Last updated was set every time the mirror object was updated. Change so that it's only updated after a successful sync.

[codecov-io]

Codecov Report

Merging #2730 into master will decrease coverage by <.01%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #2730      +/-   ##
==========================================
- Coverage   26.91%   26.91%   -0.01%     
==========================================
  Files          87       87              
  Lines       17285    17286       +1     
==========================================
  Hits         4652     4652              
- Misses      11954    11955       +1     
  Partials      679      679

Impacted Files	Coverage Δ
models/repo_mirror.go	0.62% <0%> (-0.01%)	⬇️

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[pgaskin]

Trusted LGTM, but a question: what is considered a successful sync? When a commit is added? When git returns no errors? Something else?

[lafriks]

LGTM - @geek1011 successful sync is when sync ends without errors (even if there was nothing new)

[cez81]

@geek1011 I have another issue concerning mirror last updated times, #1329. Will have look at that next.

[lafriks]

Make LG-TM work again