tests: avoid tons of spurious failures on NetBSD

* t/ax/am-test-lib.sh (process_requirements): Set the '$am_tool' variable
to the empty string before trying to unset it; otherwise, we might be
attempting to unset an already-unset variable, which (together with the
presence of the 'errexit' shell flag) causes spurious failures at least
with the /bin/sh shell from NetBSD 5.1.  This was actually causing the
great majority of the Automake tests (all those not using a "required=..."
declaration) to fail spuriously on that platform!

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>

diff --git a/t/ax/am-test-lib.sh b/t/ax/am-test-lib.sh
index ee56068..e69a904 100644 (file)
--- a/t/ax/am-test-lib.sh
+++ b/t/ax/am-test-lib.sh
@@ -740,7 +740,7 @@ process_requirements ()
   for am_tool in $*; do
     require_tool $am_tool
   done
-  unset am_tool
+  am_tool=; unset am_tool
   # We might need extra macros, e.g., from Libtool or Gettext.
   case " $required " in
     *\ libtool*) . ./t/libtool-macros.dir/get.sh;;