patch 8.2.1555: not all tests are executed on Github Actions

Problem:    Not all tests are executed on Github Actions.
Solution:   Copy "src" to "src2" earlier. Recognize "src2" in a couple more
            places.  Add two tests to the list of flaky tests. (Ken Takata,
            closes #6798)

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1555,
 /**/
     1554,
 /**/