gotest, pkg/exec: use bash instead of sh to execute shell scripts on windows

As suggested by dho, iant2.

R=golang-dev, rsc
CC=devon.odell, golang-dev, iant
https://golang.org/cl/4515147

src/cmd/gotest/gotest.go

@@ -285,8 +285,8 @@ func doRun(argv []string, returnStdout bool) string {
 			}
 			cmd += `"` + v + `"`
 		}
-		command = "sh"
-		argv = []string{"sh", "-c", cmd}
+		command = "bash"
+		argv = []string{"bash", "-c", cmd}
 	}
 	var err os.Error
 	argv[0], err = exec.LookPath(argv[0])

src/pkg/exec/exec_test.go

@@ -39,7 +39,7 @@ func TestRunCat(t *testing.T) {
 }
 
 func TestRunEcho(t *testing.T) {
-	cmd, err := run([]string{"sh", "-c", "echo hello world"},
+	cmd, err := run([]string{"bash", "-c", "echo hello world"},
 		DevNull, Pipe, DevNull)
 	if err != nil {
 		t.Fatal("run:", err)
@@ -57,7 +57,7 @@ func TestRunEcho(t *testing.T) {
 }
 
 func TestStderr(t *testing.T) {
-	cmd, err := run([]string{"sh", "-c", "echo hello world 1>&2"},
+	cmd, err := run([]string{"bash", "-c", "echo hello world 1>&2"},
 		DevNull, DevNull, Pipe)
 	if err != nil {
 		t.Fatal("run:", err)
@@ -75,7 +75,7 @@ func TestStderr(t *testing.T) {
 }
 
 func TestMergeWithStdout(t *testing.T) {
-	cmd, err := run([]string{"sh", "-c", "echo hello world 1>&2"},
+	cmd, err := run([]string{"bash", "-c", "echo hello world 1>&2"},
 		DevNull, Pipe, MergeWithStdout)
 	if err != nil {
 		t.Fatal("run:", err)
@@ -97,7 +97,7 @@ func TestAddEnvVar(t *testing.T) {
 	if err != nil {
 		t.Fatal("setenv:", err)
 	}
-	cmd, err := run([]string{"sh", "-c", "echo $NEWVAR"},
+	cmd, err := run([]string{"bash", "-c", "echo $NEWVAR"},
 		DevNull, Pipe, DevNull)
 	if err != nil {
 		t.Fatal("run:", err)