Add test for AsyncLog respecting GIT_DIR #76

Job	Run time
build-linux-arm (nightly)	18m 33s
build-linux-musl (nightly)	9m 46s
build (ubuntu-latest, nightly)	8m 42s
build-linux-arm (stable)	17m 54s
build-linux-musl (stable)	9m 59s
build (ubuntu-latest, stable)	8m 39s
build-linux-arm (1.70)	18m 42s
build-linux-musl (1.70)	10m 6s
build-apple-x86 (nightly)	5m 20s
build (ubuntu-latest, 1.70)	8m 42s
build-apple-x86 (stable)	4m 55s
build (macos-latest, nightly)	6m 47s
Lints	3m 21s
build-apple-x86 (1.70)	5m 17s
build (macos-latest, stable)	6m 29s
Changelog Test	5s
build (macos-latest, 1.70)	8m 49s
build (windows-latest, nightly)	28m 58s
udeps	8m 20s
build (windows-latest, stable)	30m 23s
build (windows-latest, 1.70)	29m 33s
	4h 9m 20s

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