builddeb: use the os codename instead of 'unstable'

This fixes a lintian error (and indeed, launchpad rejects it) by using the
distribution's codename (e.g. xenial, trusty, etc).

contrib/builddeb

@@ -1,90 +1,91 b''
 #!/bin/sh -e
 #
 # Build a Mercurial debian package from the current repo
 #
 # Tested on Jessie (stable as of original script authoring.)
 
 . $(dirname $0)/packagelib.sh
 
 BUILD=1
 CLEANUP=1
 DISTID=`(lsb_release -is 2> /dev/null | tr '[:upper:]' '[:lower:]') || echo debian`
 CODENAME=`lsb_release -cs 2> /dev/null || echo unknown`
 while [ "$1" ]; do
     case "$1" in
     --distid )
         shift
         DISTID="$1"
         shift
         ;;
     --codename )
         shift
         CODENAME="$1"
         shift
         ;;
     --cleanup )
         shift
         BUILD=
         ;;
     --build )
         shift
         CLEANUP=
         ;;
     * )
         echo "Invalid parameter $1!" 1>&2
         exit 1
         ;;
     esac
 done
 
 trap "if [ '$CLEANUP' ] ; then rm -r '$PWD/debian' ; fi" EXIT
 
 set -u
 
 if [ ! -d .hg ]; then
     echo 'You are not inside a Mercurial repository!' 1>&2
     exit 1
 fi
 
 gethgversion
 debver="$version"
 if [ -n "$type" ] ; then
     debver="$debver~$type"
 fi
 if [ -n "$distance" ] ; then
     debver="$debver+$distance-$node"
 fi
 
 control=debian/control
 changelog=debian/changelog
 
 if [ "$BUILD" ]; then
     if [ -d debian ] ; then
         echo "Error! debian control directory already exists!"
         exit 1
     fi
 
     cp -r $PWD/contrib/debian debian
     chmod -R 0755 debian
 
     sed -i.tmp "s/__VERSION__/$debver/" $changelog
     sed -i.tmp "s/__DATE__/$(date --rfc-2822)/" $changelog
+    sed -i.tmp "s/__CODENAME__/$CODENAME/" $changelog
     rm $changelog.tmp
 
     debuild -us -uc -b
     if [ $? != 0 ]; then
         echo 'debuild failed!'
         exit 1
     fi
 
 fi
 if [ "$CLEANUP" ] ; then
     echo
     OUTPUTDIR=${OUTPUTDIR:=packages/$DISTID-$CODENAME}
     mkdir -p "$OUTPUTDIR"
     find ../mercurial*.deb ../mercurial_*.build ../mercurial_*.changes \
           -type f -newer $control -print0 | \
       xargs -Inarf -0 mv narf "$OUTPUTDIR"
     echo "Built packages for $debver:"
     find "$OUTPUTDIR" -type f -newer $control -name '*.deb'
 fi

contrib/debian/changelog

@@ -1,5 +1,5 b''
-mercurial (__VERSION__) unstable; urgency=medium
+mercurial (__VERSION__) __CODENAME__; urgency=medium
 
   * Automated build performed by upstream.
 
  -- Mercurial Devel <[e-mail]>  __DATE__