hush: fix "while false; ..." exitcode; add testsuites

shell/hush.c

@@ -2305,9 +2305,11 @@ static int run_list(struct pipe *pi)
 #endif
 #if ENABLE_HUSH_LOOPS
 		if (rword == RES_WHILE) {
-			if (rcode)
+			if (rcode) {
+				rcode = 0; /* "while false; do...done" - exitcode 0 */
 				goto check_jobs_and_break;
 			}
+		}
 		if (rword == RES_UNTIL) {
 			if (!rcode) {
  check_jobs_and_break:

shell/hush_test/hush-misc/break4.right

@@ -0,0 +1,6 @@
+A
+AA
+TRUE
+A
+AA
+OK:0

shell/hush_test/hush-misc/break4.tests

@@ -0,0 +1,12 @@
+cond=true
+while $cond; do
+    echo A
+    if test "$cond" = true; then
+	cond='echo TRUE'
+    else
+	cond=false
+    fi
+    while true; do echo AA; continue 2; echo BB; done
+    echo B
+done
+echo OK:$?

shell/hush_test/hush-misc/while1.right

@@ -0,0 +1 @@
+OK:0

shell/hush_test/hush-misc/while1.tests

@@ -0,0 +1,2 @@
+while false; do echo NOT SHOWN; done
+echo OK:$?