Follow-up Comment #2, bug #42318 (project findutils):
POSIX states:
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/find.html
-xdev
The primary shall always evaluate as true; it shall cause find not
to continue descending past directories that have a different device
Follow-up Comment #1, bug #42318 (project findutils):
Should be renamed to:
"find -mount (or -xdev) is listing permission for root directory of other
mounted filesystem."
https://www.gnu.org/software/findutils/manual/html_mono/find.html#Filesystems
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[...]
Don't descend directories on other
