Correct number of braces for error message

src/main/java/com/samskivert/mustache/Mustache.java

@@ -457,7 +457,7 @@ public class Mustache
                                 int end3 = (char)source.read();
                                 if (end3 != '}') {
                                     throw new MustacheParseException(
-                                        "Invalid triple-mustache tag: {{{" + text + "}}", line);
+                                        "Invalid triple-mustache tag: {{{" + text.substring(1) + "}}", line);
                                 }
                             } catch (IOException e) {
                                 throw new MustacheException(e);

src/test/java/com/samskivert/mustache/MustacheTest.java

@@ -583,6 +583,15 @@ public class MustacheTest
              });
     }
 
+    @Test public void testInvalidTripleMustache () {
+        try {
+            Mustache.compiler().compile("{{{foo}}");
+            fail("Expected MustacheParseException");
+        } catch (MustacheParseException e) {
+            assertEquals("Invalid triple-mustache tag: {{{foo}} @ line 1", e.getMessage());
+        }
+    }
+
     @Test public void testNullValueGetsNullDefault () {
         test(Mustache.compiler().nullValue("foo"),
              "foobar", "{{nullvar}}{{nonnullvar}}", new Object() {