47514942 switched merger verification from exec to spawn-based
execWithProcessGroup, but restart.integration.test.ts only mocked
execSync/exec. spawn() returned undefined, so the merger crashed before
running the test command and any in-review merge test that hit the
verification path failed with VerificationError.
Adds a spawn mock that funnels through the existing execSync mock so a
single mockedExecSync.mockImplementation continues to control both git
calls and verification command outcomes.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
fe1bbda9ec