docker: match more version of 'hg docker version' (issue4967)

My version of docker (1.8.3) have a different formating for 'docker version'
that broke the build script. We make the version matching more generic in to
work with both version.

contrib/dockerlib.sh

@@ -1,42 +1,42 b''
 #!/bin/sh -eu
 
 # This function exists to set up the DOCKER variable and verify that
 # it's the binary we expect. It also verifies that the docker service
 # is running on the system and we can talk to it.
 function checkdocker() {
   if which docker.io >> /dev/null 2>&1 ; then
     DOCKER=docker.io
   elif which docker >> /dev/null 2>&1 ; then
     DOCKER=docker
   else
     echo "Error: docker must be installed"
     exit 1
   fi
 
   $DOCKER -h 2> /dev/null | grep -q Jansens && { echo "Error: $DOCKER is the Docking System Tray - install docker.io instead"; exit 1; }
-  $DOCKER version | grep -q "^Client version:" || { echo "Error: unexpected output from \"$DOCKER version\""; exit 1; }
-  $DOCKER version | grep -q "^Server version:" || { echo "Error: could not get docker server version - check it is running and your permissions"; exit 1; }
+  $DOCKER version | grep -Eq "^Client( version)?:" || { echo "Error: unexpected output from \"$DOCKER version\""; exit 1; }
+  $DOCKER version | grep -Eq "^Server( version)?:" || { echo "Error: could not get docker server version - check it is running and your permissions"; exit 1; }
 }
 
 # Construct a container and leave its name in $CONTAINER for future use.
 function initcontainer() {
   [ "$1" ] || { echo "Error: platform name must be specified"; exit 1; }
 
   DFILE="$ROOTDIR/contrib/docker/$1"
   [ -f "$DFILE" ] || { echo "Error: docker file $DFILE not found"; exit 1; }
 
   CONTAINER="hg-dockerrpm-$1"
   DBUILDUSER=build
   (
     cat $DFILE
     if [ $(uname) = "Darwin" ] ; then
         # The builder is using boot2docker on OS X, so we're going to
         # *guess* the uid of the user inside the VM that is actually
         # running docker. This is *very likely* to fail at some point.
         echo RUN useradd $DBUILDUSER -u 1000
     else
         echo RUN groupadd $DBUILDUSER -g `id -g` --non-unique
         echo RUN useradd $DBUILDUSER -u `id -u` -g $DBUILDUSER --non-unique
     fi
   ) | $DOCKER build --tag $CONTAINER -
 }