[yelp-tools] Fully fix warnings when there are no stack files

[Shaun McCance <shaunm src gnome org>]

commit 33c0f11607d4aa8404e92fdad09b4fa20eb6a0b2
Author: Shaun McCance <shaunm redhat com>
Date:   Wed Jun 12 16:14:46 2019 -0400

    Fully fix warnings when there are no stack files
    
    Previous fix had a mistake. I added a check in two places, did some copy pasta,
    and failed to change a variable name.

 tools/yelp-build.in | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/tools/yelp-build.in b/tools/yelp-build.in
index 8438a23..f3e21d8 100755
--- a/tools/yelp-build.in
+++ b/tools/yelp-build.in
@@ -195,7 +195,7 @@ yelp_cache_in () {
                 yelp_cache_in_site "$page"
             else
                 for sub in "$page"/*.page "$page"/*.stack; do
-                    if [ -e "$page" ]; then
+                    if [ -e "$sub" ]; then
                         yelp_cache_in_page "$sub"
                     fi
                 done