The bug appears when trying to use a filename given as:
file:///path/to/xmf/file.xmf and the xmf contains a reference to an h5 file.

- When writing you will end up with a file called 'file:' which contains
random data.
- When reading, libxml2 has no problem opening the xml file however
getRealPath() returns the wrong path for the h5 file. If you try to
use file.xmf from the to directory (ie: read("to/xmf/file.xmf")) the
h5 file will be loaded from 'to/file.h5'.

To correct the issue, we strip out the unwanted scheme and other stuff
in the URI and just use the path. (libxml has functions for this)