t / t4110 / patch2.patchon commit try_remove_empty_parents(): teach to remove parents of reflogs, too (a8f0db2)
   1diff --git a/new.txt b/new.txt
   2--- a/new.txt
   3+++ b/new.txt
   4@@ -1,7 +1,3 @@
   5-a1
   6-a11
   7-a111
   8-a1111
   9 b1
  10 b11
  11 b111