os/user: skip Current test on android

Also, add more failure output to debug why linux/mips64le and
linux/ppc64 are failing. They should be working. I suspect their
builder test envs are missing something.

Change-Id: I97273fe72c4e3009db400394636d0da1ef147485
Reviewed-on: https://go-review.googlesource.com/20358
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/os/user/lookup_stubs.go

@@ -43,7 +43,7 @@ func current() (*User, error) {
 	if u.Uid != "" && u.Username != "" && u.HomeDir != "" {
 		return u, nil
 	}
-	return nil, fmt.Errorf("user: Current not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
+	return u, fmt.Errorf("user: Current not implemented on %s/%s", runtime.GOOS, runtime.GOARCH)
 }
 
 func lookupUser(username string) (*User, error) {

src/os/user/user_test.go

@@ -16,9 +16,12 @@ func checkUser(t *testing.T) {
 }
 
 func TestCurrent(t *testing.T) {
+	if runtime.GOOS == "android" {
+		t.Skipf("skipping on %s", runtime.GOOS)
+	}
 	u, err := Current()
 	if err != nil {
-		t.Fatalf("Current: %v", err)
+		t.Fatalf("Current: %v (got %#v)", err, u)
 	}
 	if u.HomeDir == "" {
 		t.Errorf("didn't get a HomeDir")