Bug 1719622 - Upgrade mercurial to 5.8.1 in docker images. r=sheehan

Explicitly add python2 to some docker images because it was
previously installed as a side effect of installing mercurial and is
required.

Differential Revision: https://phabricator.services.mozilla.com/D119379

taskcluster/ci/packages/debian.yml

@@ -26,8 +26,8 @@ deb10-mercurial:
     run:
         dist: buster
         tarball:
-            url: https://www.mercurial-scm.org/release/mercurial-4.8.1.tar.gz
-            sha256: 48a45f5cde9104fbc2daf310d710d4ebf286d879b89fa327d24b005434b0fa21
+            url: https://www.mercurial-scm.org/release/mercurial-5.8.1.tar.gz
+            sha256: 81baa3fe2087bdda2dd119d7ea948f6badebaeb7b528a7d18b277e2ceb22b19b
         pre-build-command: >-
             cp -r contrib/packaging/debian debian &&
             sed -i -e "s/__VERSION__/$(awk -F\" '$2 {print $2}' mercurial/__version__.py)-1.deb10moz1/" \

taskcluster/ci/packages/ubuntu.yml

@@ -45,8 +45,8 @@ ub18-mercurial:
         symbol: Ub18(hg)
     run:
         tarball:
-            url: https://www.mercurial-scm.org/release/mercurial-4.8.1.tar.gz
-            sha256: 48a45f5cde9104fbc2daf310d710d4ebf286d879b89fa327d24b005434b0fa21
+            url: https://www.mercurial-scm.org/release/mercurial-5.8.1.tar.gz
+            sha256: 81baa3fe2087bdda2dd119d7ea948f6badebaeb7b528a7d18b277e2ceb22b19b
         pre-build-command: >-
             cp -r contrib/packaging/debian debian &&
             sed -i -e "s/__VERSION__/$(awk -F\" '$2 {print $2}' mercurial/__version__.py)-1.ub18moz1/" \
@@ -71,11 +71,10 @@ ub20-mercurial:
         symbol: Ub20(hg)
     run:
         tarball:
-            url: https://www.mercurial-scm.org/release/mercurial-4.8.1.tar.gz
-            sha256: 48a45f5cde9104fbc2daf310d710d4ebf286d879b89fa327d24b005434b0fa21
+            url: https://www.mercurial-scm.org/release/mercurial-5.8.1.tar.gz
+            sha256: 81baa3fe2087bdda2dd119d7ea948f6badebaeb7b528a7d18b277e2ceb22b19b
         dist: focal
         pre-build-command: >-
-            apt-get install python-is-python2 &&
             cp -r contrib/packaging/debian debian &&
             sed -i -e "s/__VERSION__/$(awk -F\" '$2 {print $2}' mercurial/__version__.py)-1.ub20moz1/" \
                          -e "s/__DATE__/$(date --rfc-2822)/" \

taskcluster/docker/toolchain-build/Dockerfile

@@ -35,6 +35,7 @@ RUN apt-get update && \
       p7zip-full \
       pkg-config \
       procps \
+      python2 \
       python3-distutils-extra \
       python3-requests \
       python3-pytoml \

taskcluster/docker/update-verify/system-setup.sh

@@ -10,6 +10,7 @@ cd /setup
 apt_packages=()
 apt_packages+=('curl')
 apt_packages+=('locales')
+apt_packages+=('python2')
 apt_packages+=('python3-pip')
 apt_packages+=('shellcheck')
 apt_packages+=('sudo')

taskcluster/taskgraph/transforms/job/common.py

@@ -113,6 +113,12 @@ def support_vcs_checkout(config, job, taskdesc, sparse=False):
     if sparse:
         cache_name += "-sparse"
 
+    # Workers using Mercurial >= 5.8 will enable revlog-compression-zstd, which
+    # workers using older versions can't understand, so they can't share cache.
+    # At the moment, only docker workers use the newer version.
+    if is_docker:
+        cache_name += "-hg58"
+
     add_cache(job, taskdesc, cache_name, checkoutdir)
 
     taskdesc["worker"].setdefault("env", {}).update(