ui: swallow EBADF on stderr ui.write_err already swallows EPIPE and EIO if a write to stderr fails. On Mac OS X at least, a write to a closed file descriptor results in EBADF. Before this patch, hg would exit with status 1 if a write to stderr failed during startup (e.g. while trying to print a warning about not finding an extension): $ ./hg --config extensions.foo= version 2>&-; echo $? 1 With this patch, it correctly swallows stderr and continues to run the command: $ ./hg --config extensions.foo= version 2>&- Mercurial Distributed SCM (version 2.1) ...