build: rerun bootstrap if AUTHORS is missing

Ever since commit 7b21981c started generating AUTHORS, we now have
the situation that if you flip between two branches in the same
git repository that cross that commit boundary, then 'make' will
fail due to automake complaining about AUTHORS not existing.  The
simplest solution is to realize that if AUTHORS does not exist,
then we flipped branches so we will need to rerun bootstrap
anyways; and rerunning bootstrap ensures AUTHORS will exist in time.

* cfg.mk (_update_required): Also depend on AUTHORS.
(cherry picked from commit 71d125620d0d88f15288aa7c2570988cc908ed11)

diff --git a/cfg.mk b/cfg.mk
index 50e6a50c69b015f424ef2b14949e7f420be28526..cd33fcfa7298ea051d3c2ad80ef78ed90724469b 100644 (file)
--- a/cfg.mk
+++ b/cfg.mk
@@ -690,6 +690,7 @@ ifeq (0,$(MAKELEVEL))
       cd '$(srcdir)';                                                  \
       test -d .git || { echo 0; exit; };                               \
       test -f po/Makevars || { echo 1; exit; };                                \
+      test -f AUTHORS || { echo 1; exit; };                            \
       actual=$$(git submodule status | $(_submodule_hash);             \
                git hash-object bootstrap.conf;                         \
                git ls-tree -d HEAD gnulib/local | awk '{print $$3}';   \