cmd/go: convert TestNonCanonicalImportPaths to a script test

This test failed in a pending CL, and I would rather debug it as a script.

Change-Id: I231367c86415ab61d0f9e08b88c9546d32b373b7
Reviewed-on: https://go-review.googlesource.com/c/go/+/206498
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/go/go_test.go

@@ -1436,17 +1436,6 @@ func TestRelativeImportsInCommandLinePackage(t *testing.T) {
 	tg.run(append([]string{"test"}, files...)...)
 }
 
-func TestNonCanonicalImportPaths(t *testing.T) {
-	tg := testgo(t)
-	defer tg.cleanup()
-	tg.parallel()
-	tg.setenv("GOPATH", filepath.Join(tg.pwd(), "testdata"))
-	tg.runFail("build", "canonical/d")
-	tg.grepStderr("package canonical/d", "did not report canonical/d")
-	tg.grepStderr("imports canonical/b", "did not report canonical/b")
-	tg.grepStderr("imports canonical/a/: non-canonical", "did not report canonical/a/")
-}
-
 func TestVersionControlErrorMessageIncludesCorrectDirectory(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()

src/cmd/go/testdata/script/noncanonical_import.txt

@@ -0,0 +1,21 @@
+env GO111MODULE=off
+
+! go build canonical/d
+stderr 'package canonical/d'
+stderr 'imports canonical/b'
+stderr 'imports canonical/a/: non-canonical'
+
+-- canonical/a/a.go --
+package a
+
+import _ "c"
+-- canonical/b/b.go --
+package b
+
+import _ "canonical/a/"
+-- canonical/a/vendor/c/c.go --
+package c
+-- canonical/d/d.go --
+package d
+
+import _ "canonical/b"

src/cmd/go/testdata/src/canonical/a/a.go

@@ -1,3 +0,0 @@
-package a
-
-import _ "c"

src/cmd/go/testdata/src/canonical/a/vendor/c/c.go

@@ -1 +0,0 @@
-package c

src/cmd/go/testdata/src/canonical/b/b.go

@@ -1,3 +0,0 @@
-package b
-
-import _ "canonical/a/"

src/cmd/go/testdata/src/canonical/d/d.go

@@ -1,3 +0,0 @@
-package d
-
-import _ "canonical/b"