Bug 1410773: Add optional comm-central virtualenv manifest; r=nalexander

comm-central taskcluster builds have comm-central checkout in `comm/`.  This
will add packages specified in comm-central when it checked out, and will
ignore the missing file for mozilla-central builds.

MozReview-Commit-ID: Amg5vJHoWkS

--HG--
extra : rebase_source : 440e1bab50c2185d18f18f7acaea83a24f0d0aaf

build/mach_bootstrap.py

@@ -122,7 +122,14 @@ def search_path(mozilla_dir, packages_txt):
     with open(os.path.join(mozilla_dir, packages_txt)) as f:
         packages = [line.rstrip().split(':') for line in f]
 
-    for package in packages:
+    def handle_package(package):
+        if package[0] == 'optional':
+            try:
+                for path in handle_package(package[1:]):
+                    yield path
+            except:
+                pass
+
         if package[0] == 'packages.txt':
             assert len(package) == 2
             for p in search_path(mozilla_dir, package[1]):
@@ -132,6 +139,10 @@ def search_path(mozilla_dir, packages_txt):
             assert len(package) == 2
             yield os.path.join(mozilla_dir, package[1])
 
+    for package in packages:
+        for path in handle_package(package):
+            yield path
+
 
 def bootstrap(topsrcdir, mozilla_dir=None):
     if mozilla_dir is None:

build/virtualenv_packages.txt

@@ -57,3 +57,4 @@ mozilla.pth:third_party/python/pyasn1
 mozilla.pth:third_party/python/pyasn1-modules
 mozilla.pth:third_party/python/rsa
 mozilla.pth:third_party/python/PyECC
+optional:packages.txt:comm/build/virtualenv_packages.txt