if echo $ver_date | grep '^[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]$' 2>&1 >/dev/null; then true; else
changequote([, ])dnl
AC_MSG_ERROR([failed to detect version date: check that darcs is in your path])
if echo $ver_date | grep '^[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]$' 2>&1 >/dev/null; then true; else
changequote([, ])dnl
AC_MSG_ERROR([failed to detect version date: check that darcs is in your path])