cmd/go/internal/modcmd: use the correct path in verifyMod

Fixes golang/go#26151.

Change-Id: Ibeefb1fad063bbec4085284cee39ee337a37d22d
Reviewed-on: https://go-review.googlesource.com/121975
Reviewed-by: Russ Cox <rsc@golang.org>
diff --git a/vendor/cmd/go/internal/modcmd/verify.go b/vendor/cmd/go/internal/modcmd/verify.go
index e965ac9..5330146 100644
--- a/vendor/cmd/go/internal/modcmd/verify.go
+++ b/vendor/cmd/go/internal/modcmd/verify.go
@@ -29,7 +29,7 @@
 
 func verifyMod(mod module.Version) bool {
 	ok := true
-	zip := filepath.Join(vgo.SrcMod, "cache", mod.Path, "/@v/", mod.Version+".zip")
+	zip := filepath.Join(vgo.SrcMod, "cache/download", mod.Path, "/@v/", mod.Version+".zip")
 	_, zipErr := os.Stat(zip)
 	dir := filepath.Join(vgo.SrcMod, mod.Path+"@"+mod.Version)
 	_, dirErr := os.Stat(dir)
diff --git a/vendor/cmd/go/vgo_test.go b/vendor/cmd/go/vgo_test.go
index 3798883..f374fc0 100644
--- a/vendor/cmd/go/vgo_test.go
+++ b/vendor/cmd/go/vgo_test.go
@@ -753,6 +753,9 @@
 		t.Fatalf("cannot find go.mod hash in go.sum: %v\n%s", err, data)
 	}
 
+	// Verify should work too.
+	tg.run("-vgo", "mod", "-verify")
+
 	// Even the most basic attempt to load the module graph should detect incorrect go.mod files.
 	tg.run("-vgo", "mod", "-graph") // loads module graph, is OK
 	tg.must(ioutil.WriteFile(tg.path("x/go.sum"), []byte(`github.com/pkg/errors v0.8.0 h1:WdK/asTD0HN+q6hsWO3/vpuAkAr+tw6aNJNDFFf0+qw=