Fix nsm for unencrypted connections

When connecting using a cleartext connection, nsm was erroring out and
tearing down the connection because it was trying to display
nonexistent certificate information.

* lisp/net/nsm.el (nsm-query-user): Only format certificate status
when it is valid.  (Bug#37221)
1 job for master in 58 minutes and 13 seconds (queued for 3 seconds)
Status Job ID Name Coverage
failed #3203


Name Stage Failure
test-all Test
Makefile:319: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:294: recipe for target 'check-expensive' failed
make[1]: *** [check-expensive] Error 2
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:959: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1