osutil: fix excessive decref on tuple creation failure in listdir()
The stat object would be freed on error for the same reason as the previous
patch. makestat() can be inlined, but this patch doesn't change it.
https://github.com/python/cpython/blob/2.7/Python/modsupport.c#L292
The __APPLE__ code is untested.
$ hg init
$ touch a
$ unset HGUSER
$ echo "[ui]" >> .hg/hgrc
$ echo "username= foo" >> .hg/hgrc
$ echo " bar1" >> .hg/hgrc
$ hg ci -Am m
adding a
abort: username 'foo\nbar1' contains a newline
[255]
$ rm .hg/hgrc
$ HGUSER=`(echo foo; echo bar2)` hg ci -Am m
adding a
abort: username 'foo\nbar2' contains a newline
[255]
$ hg ci -Am m -u "`(echo foo; echo bar3)`"
adding a
transaction abort!
rollback completed
abort: username 'foo\nbar3' contains a newline!
[255]