The receive- and trigger-pipe descriptors in the UNIX notifier are not set FD_CLOEXEC, so they leak to any child processes.
Unified diff against tclUnixNotfy.c rev. 1.37
You are right. And this also points to a yet undetected similar bug with standalone pipes [chan pipe]. I will fix both as soon as I get back to a unix system. Thanks !
Added similar fix for standalone pipes [chan pipe]
File Added: pipe_cloexec.patch