improved build, tested on wily and xenial

resolve-debbuilddeps.sh

@@ -16,7 +16,7 @@ if test -n "${SCHROOTNAME}"; then
   SUDO="schroot -c "${SCHROOTNAME}" -u root -d / --"
 else
   DO=""
-  if grep -q '/docker/' /proc/1/cgroup; then
+  if grep -q '/docker' /proc/1/cgroup; then
       SUDO=""
   else
       SUDO="sudo"
@@ -35,7 +35,7 @@ TO_INSTALL=
 
 if test -e debian/control.in -a ! -e debian/control; then
     for f in $(sed -n 's, *AX_DEB_DEPEND_IFEXISTS(\([^)]*\)).*,\1,p' configure.ac); do
-        if test -n "$(${DO} apt-cache policy -q ${f})" && ! "$(${DO} apt-cache policy ${f} 2>&1 | grep -q 'N: Unable to locate package')" && ! ${DO} dpkg -l "${f}"; then
+        if test -n "$(${DO} apt-cache policy -q ${f})" && ((! $(${DO} apt-cache policy ${f} 2>&1 | grep -q 'N: Unable to locate package')) && (! ${DO} dpkg -l "${f}")); then
             TO_INSTALL+=" ${f}"
         fi
     done