f352f8a0e6
This is an exact copy of the files misc/set/set{,_test}.go from
tailscale/corp@a5415daa9c, plus the
license headers.
For use in #7877
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I712d09c6d1a180c6633abe3acf8feb59b27e2866