deploy: more helpful output when kubectl fails

While debugging for PR kubernetes-csi#26 it was useful to see the actual input that
was sent to kubectl. It's still not perfect, but that's because line
numbers by kubectl refer to individual items, not the entire input,
but at least it's something.

deploy/kubernetes-1.13/deploy-hostpath.sh

@@ -88,7 +88,7 @@ run kubectl apply -f "${CSI_SNAPSHOTTER_RBAC}"
 echo "deploying hostpath components"
 for i in ${BASE_DIR}/hostpath/*.yaml; do
     echo "   $i"
-    cat "$i" | while IFS= read -r line; do
+    modified="$(cat "$i" | while IFS= read -r line; do
         if echo "$line" | grep -q '^\s*image:\s*'; then
             # Split 'image: quay.io/k8scsi/csi-attacher:v1.0.1'
             # into image (quay.io/k8scsi/csi-attacher:v1.0.1),
@@ -111,7 +111,12 @@ for i in ${BASE_DIR}/hostpath/*.yaml; do
             echo "        using $line" >&2
         fi
         echo "$line"
-    done | kubectl apply -f -
+    done)"
+    if ! echo "$modified" | kubectl apply -f -; then
+        echo "modified version of $i:"
+        echo "$modified"
+        exit 1
+    fi
 done
 
 # Wait until all pods are running. We have to make some assumptions