Fixed #26498 -- Fixed TimeField microseconds round-tripping on MySQL and SQLite.

Thanks adamchainz for the report and review.

django/db/backends/utils.py

@@ -127,7 +127,7 @@ def typecast_time(s):  # does NOT store time zone information
         seconds, microseconds = seconds.split('.')
     else:
         microseconds = '0'
-    return datetime.time(int(hour), int(minutes), int(seconds), int(float('.' + microseconds) * 1000000))
+    return datetime.time(int(hour), int(minutes), int(seconds), int((microseconds + '000000')[:6]))
 
 
 def typecast_timestamp(s):  # does NOT store time zone information

docs/releases/1.8.13.txt

@@ -9,4 +9,5 @@ Django 1.8.13 fixes several bugs in 1.8.12.
 Bugfixes
 ========
 
-* ...
+* Fixed ``TimeField`` microseconds round-tripping on MySQL and SQLite
+  (:ticket:`26498`).

docs/releases/1.9.6.txt

@@ -12,3 +12,6 @@ Bugfixes
 * Added support for relative path redirects to
   ``SimpleTestCase.assertRedirects()`` because Django 1.9 no longer converts
   redirects to absolute URIs (:ticket:`26428`).
+
+* Fixed ``TimeField`` microseconds round-tripping on MySQL and SQLite
+  (:ticket:`26498`).

tests/db_typecasts/tests.py

@@ -27,6 +27,9 @@ TEST_CASES = {
         ('00:00:12', datetime.time(0, 0, 12)),
         ('00:00:12.5', datetime.time(0, 0, 12, 500000)),
         ('7:22:13.312', datetime.time(7, 22, 13, 312000)),
+        ('12:45:30.126631', datetime.time(12, 45, 30, 126631)),
+        ('12:45:30.126630', datetime.time(12, 45, 30, 126630)),
+        ('12:45:30.123456789', datetime.time(12, 45, 30, 123456)),
     ),
     'typecast_timestamp': (
         ('', None),