The Cygwin chroot() implementation has holes (it can not restrict file
access by native Win32 programs).
-Inplace editing ( perl -i ) of files doesn't work without doing a backup
-of the file being edited ( perl -i.bak ).
+Inplace editing C<perl -i> of files doesn't work without doing a backup
+of the file being edited C<perl -i.bak> because of windowish restrictions,
+so Perl adds the C<.bak> automatically if you just use C<perl -i>.
=back