Fix corruption when using batch files with comments and broken lines.

Fix corruption when using batch files with comments and broken lines.
The problem was that length of allocation changed but caller not told.

Anyway, the patch fixes a problem resulting in a double free
that occurs when using batch files that contains a special combination
of broken up lines and comments as reported in:
http://bugs.debian.org/398912

Thanks to Michal Pokrywka <mpokrywka@hoga.pl> for testcase and information
on which conditions problem could be reproduced under.

Signed-off-by: Andreas Henriksson <andreas@fatal.se>
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>