Also use MockSystemReader in GitDateParserBadlyFormattedTest

All tests should use MockSystemReader to isolate them from the
underlying platform specifics.

GitDateParserBadlyFormattedTest wasn't using MockSystemReader which
induced Bug 420772 as a side effect since GitDateParser caches
SimpleDateFormat instances without regarding their locale. This will be
fixed in another change

Bug: 420772
Change-Id: I798e55d05730a71bb0326f80aea5488541d6c1f2
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/util/GitDateParserBadlyFormattedTest.java

@@ -48,6 +48,9 @@ import java.text.ParseException;
 import java.util.Calendar;
 import java.util.GregorianCalendar;
 
+import org.eclipse.jgit.junit.MockSystemReader;
+import org.junit.After;
+import org.junit.Before;
 import org.junit.experimental.theories.DataPoints;
 import org.junit.experimental.theories.Theories;
 import org.junit.experimental.theories.Theory;
@@ -60,6 +63,17 @@ import org.junit.runner.RunWith;
 public class GitDateParserBadlyFormattedTest {
 	private String dateStr;
 
+	@Before
+	public void setUp() {
+		MockSystemReader mockSystemReader = new MockSystemReader();
+		SystemReader.setInstance(mockSystemReader);
+	}
+
+	@After
+	public void tearDown() {
+		SystemReader.setInstance(null);
+	}
+
 	public GitDateParserBadlyFormattedTest(String dateStr) {
 		this.dateStr = dateStr;
 	}