TFS 2012 changes the URLs of TFS Web Access which is used by the link to the source file in the "Changes Summary Window".

A link to the source file has changed from:
https://<tfs-server>/tfs/web/view.aspx?path=<file path>&cs=<change set>
to:
https://<tfs-server>/tfs/DefaultCollection/RFQ-hub/_versionControl/item#path=<file path>&cs=<change set>&_a=contents

A link to the diff has changed from:
https://<tfs-server>/tfs/web/diff.aspx?opath=<file path>&ocs=<change set>&mpath=<file path>&mcs=<change set>
to:
https://<tfs-server>/tfs/DefaultCollection/RFQ-hub/_versionControl/item#cs=<change set>&path=<file path>&opath=<file path>&oversion=<change set>&mpath=<file path>&mversion=<change set>&_a=compare

TFS seems cable of remapping the link to the file but not to the diff.