Broken links to tasks in "My Tasks" view if the link to the page itself uses viewpage.action notation

Our customer has created a page that has "/" in the title i.e. "Foo / bar"

When linking to such page the URL appears as <hostname>/<contextpath>/pages/viewpage.action?pageId=NNNNNN

The page contains tasks assigned to people.

If one goes under My Profile/Tasks the "Task appears on" column has a link that simply glues "?focusedTaskId=XXX" without checking that URL already has query string started.

e.g.

<hostname>/<contextpath>/pages/viewpage.action?pageId=1016151?focusedTaskId=8

Accessing such URL results in 404 - not found error