Improve upstream specs

[spuun]

WHAT is this pull request doing?

This will hopefully fix some flakiness in a couple of the upstream specs.

HOW can this pull request be tested?

Run specs

[claude]

Claude finished @spuun's task —— View job

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Code Review Complete

Todo List

• Read and analyze spec/deduplication_spec.cr
• Read and analyze spec/spec_helper.cr
• Read and analyze spec/upstream_spec.cr
• Report findings (bugs, security, performance, error handling, Crystal anti-patterns)

Review Findings

spec/upstream_spec.cr:927 - Potential bug in assertion logic:

x_bound_from.size.should eq(9 - i + 1), "Expected #{6 - i + 1} entries in v#{i} but got #{x_bound_from.size}"

The assertion expects (9 - i + 1) but the error message says #{6 - i + 1}. This inconsistency could cause confusion during test failures and may indicate incorrect test logic.

spec/upstream_spec.cr:882 - Similar inconsistent error message pattern:

x_bound_from.size.should eq(9 - i + 1), "Expected #{9 - i + 1} entries in v#{i} but got #{x_bound_from.size}"

While this one is correct, it suggests the line 927 issue is a copy-paste error that should be fixed.

No other critical issues found. The changes appear to add proper synchronization helpers (eventually helper function) and improved test reliability patterns which should help reduce flakiness as intended.

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[spuun]

Superseded by #1492