Fix IgnoreRule#isMatch returning wrong result due to missing reset

The matcher has to be reset before using it, as was already done in the
other cases.

Bug: 423039
Change-Id: I87abaa7ad7f0aac8651db6e88d41427cacb4d776
Also-by: Ondrej Vrabec <ovrabec@netbeans.org>
Signed-off-by: Robin Stocker <robin@nibor.org>

org.eclipse.jgit.test/tst/org/eclipse/jgit/ignore/IgnoreMatcherTest.java

@@ -340,6 +340,18 @@ public class IgnoreMatcherTest {
 		assertEquals(r.getPattern(), "/patter?");
 	}
 
+	@Test
+	public void testResetState() {
+		String pattern = "/build/*";
+		String target = "/build";
+		// Don't use the assert methods of this class, as we want to test
+		// whether the state in IgnoreRule is reset properly
+		IgnoreRule r = new IgnoreRule(pattern);
+		// Result should be the same for the same inputs
+		assertFalse(r.isMatch(target, true));
+		assertFalse(r.isMatch(target, true));
+	}
+
 	/**
 	 * Check for a match. If target ends with "/", match will assume that the
 	 * target is meant to be a directory.

org.eclipse.jgit/src/org/eclipse/jgit/ignore/IgnoreRule.java

@@ -198,6 +198,7 @@ public class IgnoreRule {
 			}
 
 		} else {
+			matcher.reset();
 			matcher.append(target);
 			if (matcher.isMatch())
 				return true;