Issue 2443 - Honour SKIP_DEPENDENCY_UPDATES environment variable

ensure_dependencies.py

 #!/usr/bin/env python
 # coding: utf-8
 
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 import sys
 import os
 import posixpath
@@ skipping 16 matching lines @@
   # File to update this script from (optional)
   _self = buildtools/ensure_dependencies.py
   # Check out elemhidehelper repository into extensions/elemhidehelper directory
   # at tag "1.2".
   extensions/elemhidehelper = elemhidehelper 1.2
   # Check out buildtools repository into buildtools directory at VCS-specific
   # revision IDs.
   buildtools = buildtools hg:016d16f7137b git:f3f8692f82e5
 """
 
+SKIP_DEPENDENCY_UPDATES = os.environ.get(
+  "SKIP_DEPENDENCY_UPDATES", ""
+).lower() not in ("", "0", "false")
+
 class Mercurial():
   def istype(self, repodir):
     return os.path.exists(os.path.join(repodir, ".hg"))
 
   def clone(self, source, target):
     if not source.endswith("/"):
       source += "/"
     subprocess.check_call(["hg", "clone", "--quiet", "--noupdate", source, target])
 
   def get_revision_id(self, repo, rev=None):
@@ skipping 147 matching lines @@
 def get_repo_type(repo):
   for name, repotype in repo_types.iteritems():
     if repotype.istype(repo):
       return name
   return None
 
 def ensure_repo(parentrepo, target, roots, sourcename):
   if os.path.exists(target):
     return
 
+  if SKIP_DEPENDENCY_UPDATES:
+    logging.warning("SKIP_DEPENDENCY_UPDATES environment variable set, "
+                    "%s not cloned", target)
+    return
+
   parenttype = get_repo_type(parentrepo)
   type = None
   for key in roots:
     if key == parenttype or (key in repo_types and type is None):
       type = key
   if type is None:
     raise Exception("No valid source found to create %s" % target)
 
   postprocess_url = repo_types[type].postprocess_url
   root = postprocess_url(roots[type])
@@ skipping 19 matching lines @@
 
   if type in revisions:
     revision = revisions[type]
   elif "*" in revisions:
     revision = revisions["*"]
   else:
     logging.warning("No revision specified for repository %s (type %s), skipping update" % (target, type))
     return
 
   resolved_revision = repo_types[type].get_revision_id(target, revision)
-  if not resolved_revision:
-    logging.info("Revision %s is unknown, downloading remote changes" % revision)
-    repo_types[type].pull(target)
-    resolved_revision = repo_types[type].get_revision_id(target, revision)
+  current_revision = repo_types[type].get_revision_id(target)
+
+  if resolved_revision != current_revision:
+    if SKIP_DEPENDENCY_UPDATES:
+      logging.warning("SKIP_DEPENDENCY_UPDATES environment variable set, "
+                      "%s not checked out to %s", target, revision)
+      return
+
     if not resolved_revision:
-      raise Exception("Failed to resolve revision %s" % revision)
+      logging.info("Revision %s is unknown, downloading remote changes" % revision)
+      repo_types[type].pull(target)
+      resolved_revision = repo_types[type].get_revision_id(target, revision)
+      if not resolved_revision:
+        raise Exception("Failed to resolve revision %s" % revision)
 
-  current_revision = repo_types[type].get_revision_id(target)
-  if resolved_revision != current_revision:
     logging.info("Updating repository %s to revision %s" % (target, resolved_revision))
     repo_types[type].update(target, resolved_revision)
 
 def resolve_deps(repodir, level=0, self_update=True, overrideroots=None, skipdependencies=set()):
   config = read_deps(repodir)
   if config is None:
     if level == 0:
       logging.warning("No dependencies file in directory %s, nothing to do...\n%s" % (repodir, USAGE))
     return
   if level >= 10:
@@ skipping 55 matching lines @@
   args = parser.parse_args()
 
   if args.quiet:
     logging.disable(logging.INFO)
 
   repos = args.repos
   if not len(repos):
     repos = [os.path.dirname(__file__)]
   for repo in repos:
     resolve_deps(repo)