After sending the "clone" request to /proc/$pid/ns, the current process
will be moved to the working directory of $pid.
Otherwise the current process could still access the file and folders
on the service providing its dot, even if such service was not visible to $pid.
Also, keeping the original working directory means that the 'cd' line of the
current process's ns file would be different from that of $pid: the two ns
files must match since the command asked for a "clone".
See also https://marc.info/?l=9fans&m=150893734909969&w=2
Giacomo Tesio
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