Improve performance of isCommitPushed

[smashwilson]

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Requirements

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Description of the Change

Rework Present#isCommitPushed(sha) to only consider the push upstream of the current branch when listing remote refs that contain sha. This brings a considerable performance boost when opening CommitDetailItems in repositories that have a large number of remote refs, without actually changing any behavior because we were checking for the upstream ref in the --contains output anyway.

cc @vanessayuenn who noticed this 👀

Screenshot/Gif

N/A

Alternate Designs

N/A

Benefits

Performance gains when opening a CommitDetailItem in large repositories.

Possible Drawbacks

isCommitPushed will still return false if you open a commit that's pushed to a different remote tracking branch. This could cause surprising behavior if you use the github:open-commit action from the command palette to look at a commit from a different branch - specifically, the dotcom link won't show up even if the commit is pushed.

Applicable Issues

N/A

Metrics

N/A

Tests

I tested this out in dev mode with github/github.

Documentation

N/A

Release Notes

• Fixed a performance issue when opening commit items in repositories with large numbers of remote refs.

User Experience Research (Optional)

N/A

[codecov]

Codecov Report

Merging #2246 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2246      +/-   ##
==========================================
- Coverage   92.96%   92.95%   -0.01%     
==========================================
  Files         219      219              
  Lines       12565    12570       +5     
  Branches     1796     1798       +2     
==========================================
+ Hits        11681    11685       +4     
- Misses        884      885       +1

Impacted Files	Coverage Δ
lib/models/repository-states/present.js	100% <100%> (ø)	⬆️
lib/git-shell-out-strategy.js	99.8% <100%> (ø)	⬆️
lib/atom/gutter.js	90.47% <0%> (-2.39%)	⬇️

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