In the man page sigsetops(3), in the last paragraph under the DESCRIPTION section, is this fragment:
"or the additional glibc functions described below (sigisemptyset(), sigandset(), and sigdelset())."
In this fragment, sigdelset() should be sigorset().
Steps to Reproduce:
sent upstream (you should get an e-mail about it)
This has trickled down to the stable version now.