Prevent errors when parsing date on malformed lines

(see commit message)

I also added a minimal test case to reproduce this specific problem, but the result is that we have a test suite with only this test, so it's a bit strange.

/reviewed-on nexedi/apachedex!1

apachedex/__init__.py

@@ -764,7 +764,7 @@ logformat_dict = {
   '%b': r'(?P<bytes>[0-9-]*?)',
   '%l': r'(?P<ident>[^ ]*)',
   '%u': r'(?P<user>[^ ]*)',
-  '%t': r'\[(?P<timestamp>[^\]]*)\]',
+  '%t': r'\[(?P<timestamp>\d{2}/\w{3}/\d{4}:\d{2}:\d{2}:\d{2} [+-]\d{4})\]',
   '%r': r'(?P<request>[^"]*)', # XXX: expected to be enclosed in ". See also REQUEST_PATTERN
   '%>s': r'(?P<status>[0-9]*?)',
   '%O': r'(?P<size>[0-9-]*?)',

apachedex/tests.py

+import unittest
+import sys
+from StringIO import StringIO
+import apachedex
+
+
+class MalformedInputTestCase(unittest.TestCase):
+  def setUp(self):
+    self._original_sys_argv = sys.argv
+    self._original_sys_stdin = sys.stdin
+    self._original_sys_stderr = sys.stderr
+    self._original_sys_stdout = sys.stdout
+    sys.stderr = StringIO()
+    sys.stdout = StringIO()
+
+  def tearDown(self):
+    sys.argv = self._original_sys_argv
+    sys.stdin = self._original_sys_stdin
+    sys.stderr = self._original_sys_stderr
+    sys.stdout = self._original_sys_stdout
+
+  def test_timestamp_mixed_in_timestamp(self):
+    sys.argv = ['apachedex', '--base=/', '-']
+    sys.stdin = StringIO(
+    # this first line is valid, but second is not
+    '''127.0.0.1 - - [14/Jul/2017:09:41:41 +0200] "GET / HTTP/1.1" 200 7499 "https://example.org/" "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.112 Safari/537.36" 1754
+127.0.0.1 - - [14/Jul/2017:127.0.0.1 - - [14/Jul/2017:09:41:41 +0200] "GET / HTTP/1.1" 200 7499 "https://example.org/" "Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.112 Safari/537.36" 1754''')
+    apachedex.main()
+
+    self.assertNotIn('Malformed line at -:1', sys.stderr.getvalue())
+    self.assertIn('Malformed line at -:2', sys.stderr.getvalue())
+