db/Pad: reversed truthy condition to make core logic evident

Since the original comparison compared for truthy and not for "===", and it's
3 AM now, I blindly negated it, in order to show how fragile it was in the first
instance.

No functional changes.

This is the final commit of this refactoring series.

src/node/db/Pad.js

@@ -505,8 +505,16 @@ Pad.prototype.copy = function copy(destinationID, force, callback) {
       {
         if(ERR(err, callback)) return;
 
-        if(exists == true)
+        /*
+         * this is the negation of a truthy comparison. Has been left in this
+         * wonky state to keep the old (possibly buggy) behaviour
+         */
+        if (!(exists == true))
         {
+          callback();
+          return;
+        }
+
         if (!force)
         {
           console.error("erroring out without force");
@@ -520,11 +528,6 @@ Pad.prototype.copy = function copy(destinationID, force, callback) {
           if (ERR(err, callback)) return;
           pad.remove(callback);
         });
-        }
-        else
-        {
-          callback();
-        }
       });
     },
     // copy the 'pad' entry