x/tools/refactor/importgraph: TestBuild is failing sometimes #37823
Description
I'm seeing frequent failures that look like this at https://build.golang.org/?repo=golang.org%2fx%2ftools on the darwin builders:
--- FAIL: TestBuild (28.63s)
graph_test.go:51: forward[importgraph][go/build] not found
graph_test.go:54: reverse[go/build][importgraph] not found
graph_test.go:51: forward[importgraph][testing] not found
graph_test.go:54: reverse[testing][importgraph] not found
graph_test.go:51: forward[importgraph][crypto/hmac] not found
graph_test.go:54: reverse[crypto/hmac][importgraph] not found
graph_test.go:79: intransitive: forward.Search(importgraph)[errors] not found
graph_test.go:82: intransitive: reverse.Search(errors)[importgraph] not found
graph_test.go:79: intransitive: forward.Search(importgraph)[reflect] not found
graph_test.go:82: intransitive: reverse.Search(reflect)[importgraph] not found
graph_test.go:79: intransitive: forward.Search(importgraph)[unsafe] not found
graph_test.go:82: intransitive: reverse.Search(unsafe)[importgraph] not found
FAIL
FAIL golang.org/x/tools/refactor/importgraph 32.386s
For a recent example, see https://build.golang.org/log/5b156a1c79480768102921c27ab1b16ccc7c0590.
/cc @matloob