[tools] Don't forget to print UTest when printing aggregates only

This probably regressed in #1042.

tools/gbench/report.py

@@ -301,11 +301,8 @@ def print_difference_report(
     fmt_str = "{}{:<{}s}{endc}{}{:+16.4f}{endc}{}{:+16.4f}{endc}{:14.0f}{:14.0f}{endc}{:14.0f}{:14.0f}"
     for benchmark in json_diff_report:
         # *If* we were asked to only include aggregates,
-        # and if it is non-aggregate, then skip it.
+        # and if it is non-aggregate, then don't print it.
-        if include_aggregates_only and 'run_type' in benchmark:
+        if not include_aggregates_only or not 'run_type' in benchmark or benchmark['run_type'] != 'aggregate':
-            if benchmark['run_type'] != 'aggregate':
-                continue
-
             for measurement in benchmark['measurements']:
                 output_strs += [color_format(use_color,
                                             fmt_str,
@@ -643,6 +640,52 @@ class TestReportDifferenceWithUTest(unittest.TestCase):
             parts = [x for x in output_lines[i].split(' ') if x]
             self.assertEqual(expect_lines[i], parts)
 
+    def test_json_diff_report_pretty_printing_aggregates_only(self):
+        expect_lines = [
+            ['BM_Two', '+0.1111', '-0.0111', '9', '10', '90', '89'],
+            ['BM_Two', '-0.1250', '-0.1628', '8', '7', '86', '72'],
+            ['BM_Two_pvalue',
+             '0.6985',
+             '0.6985',
+             'U',
+             'Test,',
+             'Repetitions:',
+             '2',
+             'vs',
+             '2.',
+             'WARNING:',
+             'Results',
+             'unreliable!',
+             '9+',
+             'repetitions',
+             'recommended.'],
+            ['short_pvalue',
+             '0.7671',
+             '0.1489',
+             'U',
+             'Test,',
+             'Repetitions:',
+             '2',
+             'vs',
+             '3.',
+             'WARNING:',
+             'Results',
+             'unreliable!',
+             '9+',
+             'repetitions',
+             'recommended.'],
+            ['medium', '-0.3750', '-0.3375', '8', '5', '80', '53'],
+        ]
+        output_lines_with_header = print_difference_report(
+            self.json_diff_report, include_aggregates_only=True, utest=True, utest_alpha=0.05, use_color=False)
+        output_lines = output_lines_with_header[2:]
+        print("\n")
+        print("\n".join(output_lines_with_header))
+        self.assertEqual(len(output_lines), len(expect_lines))
+        for i in range(0, len(output_lines)):
+            parts = [x for x in output_lines[i].split(' ') if x]
+            self.assertEqual(expect_lines[i], parts)
+
     def test_json_diff_report(self):
         expected_output = [
             {