[FIX] mail: followers: allow edit subtypes even if not follower

Before this rev., editing the subtypes of other followers was only possible if
the current user already opened a record of the same model of which he is
himself follower.

addons/mail/static/src/js/followers.js

@@ -287,11 +287,6 @@ var Followers = form_common.AbstractField.extend({
         $list.empty();
 
         this.data_subtype = data;
-        this.records_length = _.map(data, function(value, index) { return index; }).length;
-
-        if (this.records_length > 1) {
-            this.display_followers();
-        }
 
         _.each(data, function (record) {
             if (old_parent_model !== record.parent_model && old_parent_model !== undefined) {

addons/mail/static/src/xml/followers.xml

@@ -42,8 +42,8 @@
                t-att-title="record.name"
                t-att-data-oe-model="record.res_model"
                t-att-data-oe-id="record.res_id"><t t-esc="record.name"/></a>
-            <i t-if="record.is_editable and (widget.records_length &gt; 1)"
-               class="fa fa-pencil o_edit_subtype hide" title="Edit subscription"
+            <i t-if="record.is_editable" class="fa fa-pencil o_edit_subtype hide"
+               title="Edit subscription"
                t-att-data-follower-id="record.id"
                t-att-data-oe-id="record.res_id"
                t-att-data-oe-model="record.res_model"/>