This is the “ignore fchmod(3p) errors” option.
By default, if the output file permissions cannot be changed to
the permissions specified in the encoded data, the file will not
be written out and execution stops. This option will cause that
error to be ignored. The resulting file will have all the data,
but the incorrect mode settings.
fchmod() errors are also ignored if
POSIXLY_CORRECT is set in the environment. RE:
<http://austingroupbugs.net/view.php?id=635>
A warning is always emitted when fchmod() fails.