tests: Use -maxdepth 0 instead of | head -n1

This avoids the potential for "broken pipe" errors observed on some
systems, e.g.

http://build.alpinelinux.org/buildlogs/build-edge-s390x/testing/bfs/bfs-1.2.2-r0.log

1 files changed, 1 insertions, 1 deletions

diff --git a/tests.sh b/tests.sh
index 9302cfc..1045e51 100755
--- a/tests.sh
+++ b/tests.sh
@@ -1342,7 +1342,7 @@ function test_printf_w() {
 }
 
 function test_fstype() {
-    fstype="$(invoke_bfs -printf '%F\n' | head -n1)"
+    fstype="$(invoke_bfs basic -maxdepth 0 -printf '%F\n')"
     bfs_diff basic -fstype "$fstype"
 }