hush: add tests for interrupting read

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/shell/hush_test/hush-trap/signal_read1.tests b/shell/hush_test/hush-trap/signal_read1.tests
new file mode 100755
index 0000000..1105479
--- /dev/null
+++ b/shell/hush_test/hush-trap/signal_read1.tests
@@ -0,0 +1,5 @@
+(sleep 1; kill -HUP $$) &
+trap 'echo "Got HUP:$?"; exit' HUP
+while true; do
+	read ignored
+done