Bug 1560826 - Make bootstrap upgrade mercurial when it is older than 4.8. r=nalexander

4.3.3 is the strict minimum required for v-c-t's config wizard, but it
is preferable people use more modern versions. We could go with 5.0, but
it feels like people still using 4.8 and 4.9 don't really need to be
bugged to update to a more recent version, they are kind of modern
enough. OTOH MozillaBuild comes with 4.5.x, and this will force an
upgrade for those.

Differential Revision: https://phabricator.services.mozilla.com/D35756

--HG--
extra : moz-landing-system : lando

python/mozboot/mozboot/base.py

@@ -143,9 +143,7 @@ ac_add_options --enable-artifact-builds
 '''
 
 # Upgrade Mercurial older than this.
-# This should match OLDEST_NON_LEGACY_VERSION from
-# the hg setup wizard in version-control-tools.
-MODERN_MERCURIAL_VERSION = LooseVersion('4.3.3')
+MODERN_MERCURIAL_VERSION = LooseVersion('4.8')
 
 # Upgrade Python older than this.
 MODERN_PYTHON_VERSION = LooseVersion('2.7.3')