Fixed OSError "No such file or directory: None" and make IOError consistent.
The None error occurs when the current working directory is no longer
available, e.g. because it was removed in another shell.
If local repository is missing, make error message clearer.
Faheem Mitha suggested finding a better error message.
The nice error message is taken from cogito.
don't let lazyparser read more data than it can handle
This should fix
issue368.