cmd/go: reset read-only flag during TestIssue10952

git sets read-only flag on all its repo files on Windows.
os.Remove cannot delete these files.

Fixes windows build

Change-Id: Icaf72470456b88a1c26295caecd4e0d3dc22a1b6
Reviewed-on: https://go-review.googlesource.com/11602Reviewed-by: Alex Brainman <alex.brainman@gmail.com>

src/cmd/go/go_test.go

@@ -554,6 +554,32 @@ func (tg *testgoData) cleanup() {
 	}
 }
 
+// resetReadOnlyFlagAll resets windows read-only flag
+// set on path and any children it contains.
+// The flag is set by git and has to be removed.
+// os.Remove refuses to remove files with read-only flag set.
+func (tg *testgoData) resetReadOnlyFlagAll(path string) {
+	fi, err := os.Stat(path)
+	if err != nil {
+		tg.t.Fatalf("resetReadOnlyFlagAll(%q) failed: %v", path, err)
+	}
+	if !fi.IsDir() {
+		err := os.Chmod(path, 0666)
+		if err != nil {
+			tg.t.Fatalf("resetReadOnlyFlagAll(%q) failed: %v", path, err)
+		}
+	}
+	fd, err := os.Open(path)
+	if err != nil {
+		tg.t.Fatalf("resetReadOnlyFlagAll(%q) failed: %v", path, err)
+	}
+	defer fd.Close()
+	names, _ := fd.Readdirnames(-1)
+	for _, name := range names {
+		tg.resetReadOnlyFlagAll(path + string(filepath.Separator) + name)
+	}
+}
+
 // failSSH puts an ssh executable in the PATH that always fails.
 // This is to stub out uses of ssh by go get.
 func (tg *testgoData) failSSH() {
@@ -970,6 +996,7 @@ func TestIssue10952(t *testing.T) {
 	const importPath = "github.com/zombiezen/go-get-issue-10952"
 	tg.run("get", "-d", "-u", importPath)
 	repoDir := tg.path("src/" + importPath)
+	defer tg.resetReadOnlyFlagAll(repoDir)
 	tg.runGit(repoDir, "remote", "set-url", "origin", "https://"+importPath+".git")
 	tg.run("get", "-d", "-u", importPath)
 }