Quote variables, improve readability

modules/dpkg/functions/deb-history

@@ -12,13 +12,13 @@ case "$1" in
     zgrep --no-filename 'install ' $(ls -rt /var/log/dpkg*)
   ;;
   (upgrade|remove)
-    zgrep --no-filename $1 $(ls -rt /var/log/dpkg*)
+    zgrep --no-filename "$1" $(ls -rt /var/log/dpkg*)
   ;;
   (rollback)
-    zgrep --no-filename upgrade $(ls -rt /var/log/dpkg*) | \
-      grep "$2" -A10000000 | \
-      grep "$3" -B10000000 | \
-      awk '{print $4"="$5}'
+    zgrep --no-filename upgrade $(ls -rt /var/log/dpkg*) \
+      | grep "$2" -A10000000 \
+      | grep "$3" -B10000000 \
+      | awk '{print $4"="$5}'
   ;;
   (list)
     zcat $(ls -rt /var/log/dpkg*)