Change shebang to bash since -p option is used in read command,
use $(..) instead of `..`,
double quote to prevent word splitting,
handle cd failure.

Change-Id: I2ae00bbd21754136610504f2ff6818b8d3695cc4
Reviewed-on: https://gerrit.libreoffice.org/33089Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: jan iversen <jani@documentfoundation.org>