R1:ac1c9559860b

Transactions - fix bug in differential where older inlines weren't appearing

Summary: Fixes T6699. We need to "loadInlineComments" consistently, though for an unexpected reason - this mutates the $changesets to include all $changesets that have an associated inline comment, which is necessary to make them render properly.

Test Plan: Took a diff with inline comments and updated it, noting the inline comments disappeared. applied this patch and the inlines reappeared.

Reviewers: epriestley

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