Fix HistoryEntry corruption when commit isn't for provisional entry (try #2).

      BUG=597322, 600238
TEST=See bug for repro steps.
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_site_isolation

Review URL: https://codereview.chromium.org/1848813005

Cr-Commit-Position: refs/heads/master@{#386785}