t / t4101 / diff.0-2on commit revision.h: make show_early_output an extern which is defined in revision.c (4dc1db0)
   1--- a/frotz
   2+++ b/frotz
   3@@ -1,2 +1,2 @@
   4 a
   5-b
   6+b
   7\ No newline at end of file