rules.tags: Behave like rules.tag

One did try to match tag by name and the other didn't.

While at it, also ensure that the screen is consistent.

lib/awful/rules.lua

@@ -376,13 +376,31 @@ function rules.extra_properties.placement(c, value)
     end
 end
 
-function rules.extra_properties.tags(c, value)
+function rules.extra_properties.tags(c, value, props)
     local current = c:tags()
 
+    local tags, s = {}, nil
+
+    for _, t in ipairs(value) do
+        if type(t) == "string" then
+            t = atag.find_by_name(c.screen, t)
+        end
+
+        if t and ((not s) or t.screen == s) then
+            table.insert(tags, t)
+            s = s or t.screen
+        end
+    end
+
+    if s and s ~= c.screen then
+        c.screen = s
+        props.screen = s -- In case another rule query it
+    end
+
     if #current == 0 or (value[1] and value[1].screen ~= current[1].screen) then
-        c:tags(value)
+        c:tags(tags)
     else
-        c:tags(util.table.merge(current, value))
+        c:tags(util.table.merge(current, tags))
     end
 end
 
@@ -477,7 +495,7 @@ function rules.execute(c, props, callbacks)
 
         if not ignore then
             if rules.extra_properties[property] then
-                rules.extra_properties[property](c, value)
+                rules.extra_properties[property](c, value, props)
             elseif type(c[property]) == "function" then
                 c[property](c, value)
             else