Fix LimitDiffsByPathspec to handle exclusion-only pathspecs

[manato-tajiri]

Description

When using only exclusion pathspecs (e.g., git who table -f -n 0 ':!*.json'), the Files and Lines (+/-) columns show 0 values. This happens because the concurrent execution path post-filters diffs using LimitDiffsByPathspec(), which incorrectly initializes shouldInclude to false when no include pathspecs are present.

Root Cause

In internal/git/git.go, the LimitDiffsByPathspec function splits pathspecs into includes and excludes. When only :!*.json is provided:

• includes = [] (empty)
• excludes = ["*.json"]

The initialization shouldInclude := false means every file diff is rejected since the loop over the empty includes slice never executes.

Fix

Changed shouldInclude := false to shouldInclude := len(includes) == 0.

This ensures that when only exclusion pathspecs are provided, all files are included by default and only removed if they match an exclusion pattern. Mixed include/exclude cases continue to work as before.

Testing

• Verified on rubengmurray/no-unawaited-dot-catch-throw: git who table -f -n 0 ':!*.json' now correctly shows 9 files, 568/120 lines instead of 0/0
• Both concurrent (GOMAXPROCS=4) and non-concurrent (GOMAXPROCS=1) paths produce identical correct results
• Multiple exclusion patterns work correctly
• All unit tests pass:

  ok  github.com/sinclairtarget/git-who/internal/git    0.792s
  ok  github.com/sinclairtarget/git-who/internal/tally   1.377s
  ok  github.com/sinclairtarget/git-who/internal/format  0.660s