Add better error messages when determining merge-base #1428

Job	Run time
Go: tracing with custom build steps (ubuntu-latest, stable-20220615)	1m 5s
Go: tracing with custom build steps (macos-latest, stable-20220615)	4m 23s
Go: tracing with custom build steps (ubuntu-latest, stable-20220908)	1m 16s
Go: tracing with custom build steps (macos-latest, stable-20220908)	4m 45s
Go: tracing with custom build steps (ubuntu-latest, stable-20221211)	1m 10s
Go: tracing with custom build steps (macos-latest, stable-20221211)	4m 59s
Go: tracing with custom build steps (ubuntu-latest, stable-20230418)	1m 40s
Go: tracing with custom build steps (macos-latest, stable-20230418)	4m 49s
Go: tracing with custom build steps (ubuntu-latest, default)	1m 34s
Go: tracing with custom build steps (macos-latest, default)	5m 14s
Go: tracing with custom build steps (ubuntu-latest, latest)	1m 13s
Go: tracing with custom build steps (macos-latest, latest)	5m 13s
Go: tracing with custom build steps (ubuntu-latest, nightly-latest)	1m 30s
Go: tracing with custom build steps (macos-latest, nightly-latest)	4m 22s
	43m 13s

Provide feedback