tests: fix prints
- delete unnecessary newlines
- make sure formatted prints call the formatting routines

R=adg
CC=golang-dev
https://golang.org/cl/2225046
diff --git a/src/pkg/unicode/digit_test.go b/src/pkg/unicode/digit_test.go
index 57a625b..9bbccde 100644
--- a/src/pkg/unicode/digit_test.go
+++ b/src/pkg/unicode/digit_test.go
@@ -106,12 +106,12 @@
 func TestDigit(t *testing.T) {
 	for _, r := range testDigit {
 		if !IsDigit(r) {
-			t.Errorf("IsDigit(U+%04X) = false, want true\n", r)
+			t.Errorf("IsDigit(U+%04X) = false, want true", r)
 		}
 	}
 	for _, r := range testLetter {
 		if IsDigit(r) {
-			t.Errorf("IsDigit(U+%04X) = true, want false\n", r)
+			t.Errorf("IsDigit(U+%04X) = true, want false", r)
 		}
 	}
 }