The registerBundleDirs method in the kernel returns array(namespace => dir, ...).
In some places dirname() is used to separate a namespace from the classname. The
resulting value contains slashes rather than backslashes, causing look ups in the
bundle dirs array to fail.
I assume this was not noticed so far because it requires that you use one of the
features making this mistake with a bundle inside a subnamespace, as top level
namespaces will not contain a backslash anyway.
The Doctrine Bundle refered to "username" in some places and to user in others.
Namely the schema and the DoctrineExtension have been updated to use "user".
I chose user rather than username because Doctrine uses that term itself.