RSS Feed is Not Correctly Encoding HTML Entities

[cawoodm]

/members/cawoodm/activity/feed
This link in our BP generates an RSS feed in which german umlauts (e.g ü) are encoded as HTML entities (e.g. ü) instead of being left as they are. This makes the feed invalid because the entities are not defined.

Our site's encoding is UTF-8 and this is reflected in the HTTP Response headers (Content-Type: text/xml; charset=UTF-8). Yet BP is encoding, for example the feed title as:
<title>Marc Cawood - Aktivit&auml;t</title>
INSTEAD OF:
<title>Marc Cawood - Aktivität</title>

What is the mechanism behind this? Is it done by echo() or the mysterious function _e()?

[apeatling]

(In [1193]) Fixes #516