patch 8.1.1027: memory usage test sometimes fails

Problem:    Memory usage test sometimes fails.
Solution:   Use 80% of before.last as the lower limit. (Christian Brabandt)

src/testdir/test_memory_usage.vim

@@ -137,7 +137,9 @@ func Test_memory_func_capture_lvars()
     let last = s:monitor_memory_usage(vim.pid).last
   endfor
 
-  call assert_inrange(before, after.max + (after.last - before), last)
+  " The usage may be a bit less than the last value 
+  let lower = before * 8 / 10
+  call assert_inrange(lower, after.max + (after.last - before), last)
 
   call vim.stop()
   call delete(testfile)

src/version.c

@@ -779,6 +779,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1027,
 /**/
     1026,
 /**/