Revert "ZMySQLDA: Optimise date & datetime parsing in results."

For some reason, unit tests all broke while testing this revision. The
relation between both is not clear to me (this code has worked for me).
In doubt, I revert it for now.
This reverts commit 0057272c.

product/ZMySQLDA/db.py

@@ -158,39 +158,9 @@ def _mysql_timestamp_converter(s):
                           s[8:10],s[10:12],s[12:14]))
         return DateTime("%04d-%02d-%02d %02d:%02d:%02d" % tuple(parts))
 
-# DateTime(str) is slow. As the date format is part of the specifications,
-# parse it ourselves to save time.
-def DATETIME_to_DateTime_or_None(s):
-    try:
-        date, time = s.split(' ')
-        year, month, day = date.split('-')
-        hour, minte, second = time.split(':')
-        return DateTime(
-            int(year),
-            int(month),
-            int(day),
-            int(hour),
-            int(minute),
-            float(second),
-            'UTC',
-        )
-    except Exception:
-        return None
-
-def DATE_to_DateTime_or_None(s):
-    try:
-        year, month, day = s.split('-')
-        return DateTime(
-            int(year),
-            int(month),
-            int(day),
-            0,
-            0,
-            0,
-            'UTC',
-        )
-    except Exception:
-        return None
+def DateTime_or_None(s):
+    try: return DateTime('%s UTC' % s)
+    except Exception: return None
 
 def ord_or_None(s):
     if s is not None:
@@ -201,8 +171,8 @@ class DB(TM):
 
     conv=conversions.copy()
     conv[FIELD_TYPE.LONG] = int
-    conv[FIELD_TYPE.DATETIME] = DATETIME_to_DateTime_or_None
-    conv[FIELD_TYPE.DATE] = DATE_to_DateTime_or_None
+    conv[FIELD_TYPE.DATETIME] = DateTime_or_None
+    conv[FIELD_TYPE.DATE] = DateTime_or_None
     conv[FIELD_TYPE.DECIMAL] = float
     conv[FIELD_TYPE.BIT] = ord_or_None
     del conv[FIELD_TYPE.TIME]