Regexp of directory names which stop the search in `locate-dominating-file'.
Any directory whose name matches this regexp will be treated like
a kind of root directory by `locate-dominating-file' which will stop its search
when it bumps into it.
The default regexp prevents fruitless and time-consuming attempts to find
special files in directories in which filenames are interpreted as hostnames,
or mount points potentially requiring authentication as a different user.