more JGit related cleanup

the date parsing is no longer needed because the commit date is not parsed
from git log output anymore

Author: Vladimir Kotal

opengrok-indexer/src/main/java/org/opengrok/indexer/history/GitRepository.java

@@ -127,13 +127,6 @@ public class GitRepository extends RepositoryWithPerPartesHistory {
 
     public GitRepository() {
         type = "git";
-        /*
-         * This should match the 'iso-strict' format used by
-         * {@code getHistoryLogExecutor}.
-         */
-        datePatterns = new String[] {
-            "yyyy-MM-dd'T'HH:mm:ssXXX"
-        };
 
         ignoredDirs.add(".git");
         ignoredFiles.add(".git");

opengrok-indexer/src/test/java/org/opengrok/indexer/history/GitRepositoryTest.java

@@ -294,27 +294,6 @@ public void fileHasHistory() {
         assertTrue(result);
     }
 
-    @Test
-    public void testDateFormats() {
-        String[][] tests = new String[][] {
-                {"abcd", "expected exception"},
-                {"2016-01-01 10:00:00", "expected exception"},
-                {"2016 Sat, 5 Apr 2008 15:12:51 +0000", "expected exception"},
-                {"2017-07-25T13:17:44+02:00", null},
-        };
-
-        final GitRepository repository = new GitRepository();
-
-        for (String[] test : tests) {
-            try {
-                repository.parse(test[0]);
-                assertNull(test[1], "Shouldn't be able to parse the date: " + test[0]);
-            } catch (ParseException ex) {
-                assertNotNull(test[1], "Shouldn't throw a parsing exception for date: " + test[0]);
-            }
-        }
-    }
-
     /**
      * For the following renamed tests the structure in the git repo is as following:
      * <pre>