Adjust CircleCI config to be compatible with release branches

Add the necessary bits to the master CCI configuration to make the package
building parts also work in the release branches. This way there is no
need to tailor the release branches' CCI setup on release day.

This should not (famous last words) change how the weekly packages from
the master branch are generated.

.circleci/config.yml

@@ -7,6 +7,12 @@ parameters:
   pkg-commit:
     type: string
     default: "master"
+  dist-url:
+    type: string
+    default: ""
+  dist-url-sha256:
+    type: string
+    default: ""
   configure_args:
     type: string
     default: |
@@ -17,7 +23,7 @@ parameters:
         --with-persistent-storage \
 jobs:
   dist:
-    description: Builds varnish-x.y.z.tar.gz that is used later for the packaging jobs
+    description: Build or download varnish-x.y.z.tar.gz that is used later for the packaging jobs
     docker:
       - image: centos:7
     steps:
@@ -37,14 +43,43 @@ jobs:
                 python3 \
                 python-sphinx
       - checkout
+      - when:
+          condition: << pipeline.parameters.dist-url >>
+          steps:
+            - run:
+                name: Download the dist tarball
+                command: |
+                  curl -s << pipeline.parameters.dist-url >> -o varnish-dist.tar.gz
+            - when:
+                condition: << pipeline.parameters.dist-url-sha256 >>
+                steps:
+                  - run:
+                      name: Verify downloaded tarball
+                      command: |
+                        echo "<< pipeline.parameters.dist-url-sha256 >> varnish-dist.tar.gz" | sha256sum -c
+            - run:
+                name: Rename the dist tarball by parsed version
+                command: |
+                  mkdir parse-version-tmp
+                  cd parse-version-tmp
+                  tar xzf ../varnish-dist.tar.gz
+                  VERSION=$(varnish-*/configure --version | awk 'NR == 1 {print $NF}')
+                  cd ..
+                  mv -v varnish-dist.tar.gz varnish-${VERSION}.tar.gz
+      - unless:
+          condition: << pipeline.parameters.dist-url >>
+          steps:
             - run:
                 name: Create the dist tarball
                 command: |
                   git checkout << pipeline.parameters.vc-commit >>
-            # if version is "trunk", it's a weekly tarball, override the version
-            if grep 'AC_INIT.*trunk.*' ./configure.ac; then
-                sed -i -e "s/^AC_INIT.*trunk.*/AC_INIT([Varnish], [$(date +%Y%m%d)], [varnish-dev@varnish-cache.org])/" ./configure.ac
+                  # Locally built tarballs are always built with weekly in package name
                   touch .is_weekly
+                  # If version is "trunk", override version to add date
+                  if grep 'AC_INIT.*trunk.*' ./configure.ac; then
+                      sed -e "s/AC_INIT(\[\(.*\)\], \[\(.*\)\], \[\(.*\)\])/AC_INIT([\1], [$(date +%Y%m%d)], [\3])/" ./configure.ac
+                  else
+                      sed -e "s/AC_INIT(\[\(.*\)\], \[\(.*\)\], \[\(.*\)\])/AC_INIT([\1], [\2-$(date +%Y%m%d)], [\3])/" ./configure.ac
                   fi
                   ./autogen.des --quiet
                   make dist -j 16