util: forward __bool__()/__nonzero__() on fileobjectproxy In trying to debug the Windows process hang in D2720, I changed the stderr pipe to the peer to be os.devnull instead. That caused sshpeer._cleanuppipes()[1] to explode, complaining NoneType has no __iter__ attribute, even though the previous line checked for None. [1] https://www.mercurial-scm.org/repo/hg/file/b434965f984e/mercurial/sshpeer.py#l133