tests: init.sh: use "sed 1q" in place of "head -1"

* tests/init.sh (warn_): Use "sed 1q" in place of "head -1".
The latter is officially obsolete but more portable than "head -n1".
Reported by Bernhard Voelker.

diff --git a/tests/init.sh b/tests/init.sh
index 5878179..460937d 100644 (file)
--- a/tests/init.sh
+++ b/tests/init.sh
@@ -84,7 +84,7 @@ warn_ ()
   case $IFS in
     ' '*) printf '%s\n' "$*" >&2
           test $stderr_fileno_ = 2 \
-            || { printf '%s\n' "$*" | head -1 >&$stderr_fileno_ ; } ;;
+            || { printf '%s\n' "$*" | sed 1q >&$stderr_fileno_ ; } ;;
     *) (IFS=' '; warn_ "$@");;
   esac
 }