Error codes meaning "This is a working copy, but I can't read it"

[Daniel Shahaf <d....@daniel.shahaf.name>]

I'm looking into a piece of logic for extracting basic information about
a working copy (basically, the output of `svn info` on the the current
directory or on the wc root), and trying to teach it to detect the
situation "This is a working copy, but I can't read it".

What error codes should I look for?  In a few test cases I managed to
get straight `svn info` to report SVN_ERR_WC_UPGRADE_REQUIRED,
SVN_ERR_WC_UNSUPPORTED_FORMAT, and SVN_ERR_WC_CORRUPT on the one hand,
and SVN_ERR_WC_NOT_WORKING_COPY on the other hand, and I'm sure there
are more...

Thanks,

Daniel