Stopped stripping microseconds with MySQL backend

Refs #19716.

django/db/backends/mysql/base.py

@@ -364,8 +364,7 @@ class DatabaseOperations(BaseDatabaseOperations):
             else:
                 raise ValueError("MySQL backend does not support timezone-aware datetimes when USE_TZ is False.")
 
-        # MySQL doesn't support microseconds
-        return six.text_type(value.replace(microsecond=0))
+        return six.text_type(value)
 
     def value_to_db_time(self, value):
         if value is None:
@@ -375,13 +374,7 @@ class DatabaseOperations(BaseDatabaseOperations):
         if timezone.is_aware(value):
             raise ValueError("MySQL backend does not support timezone-aware times.")
 
-        # MySQL doesn't support microseconds
-        return six.text_type(value.replace(microsecond=0))
-
-    def year_lookup_bounds_for_datetime_field(self, value):
-        # Again, no microseconds
-        first, second = super(DatabaseOperations, self).year_lookup_bounds_for_datetime_field(value)
-        return [first.replace(microsecond=0), second.replace(microsecond=0)]
+        return six.text_type(value)
 
     def max_name_length(self):
         return 64

docs/releases/1.8.txt

@@ -160,6 +160,14 @@ Cache
 * The ``incr()`` method of the
   ``django.core.cache.backends.locmem.LocMemCache`` backend is now thread-safe.
 
+Database backends
+^^^^^^^^^^^^^^^^^
+
+* The MySQL backend no longer strips microseconds from ``datetime`` values as
+  MySQL 5.6.4 and up supports fractional seconds depending on the declaration
+  of the datetime field (when ``DATETIME`` includes fractional precision greater
+  than 0).
+
 Email
 ^^^^^