Add option for git-repo to support 'silent' uploads

When --ne/--no-emails is added to 'repo upload' command line, gerrit
server will not generate notification emails.

project.py:Project.UploadForReview method is modified to accept a
string recognizable by gerrit to indicate different sets of destination
email addressees, but the upload command line allows only one option -
disable sending emails completely.

Default repo upload behavior is not being changed.

TEST=tried in the Chrome OS repo, observed that patches uploaded with
     --ne or --no-emails indeed do not trigger any emails, while
     patches uploaded without these command line options still trigger
     email notifications.

Change-Id: I0301edec984907aedac277d883bd0e6d3099aedc

project.py

@@ -176,6 +176,7 @@ class ReviewableBranch(object):
                       auto_topic=False,
                       draft=False,
                       private=False,
+                      notify=None,
                       wip=False,
                       dest_branch=None,
                       validate_certs=True,
@@ -185,6 +186,7 @@ class ReviewableBranch(object):
                                  auto_topic=auto_topic,
                                  draft=draft,
                                  private=private,
+                                 notify=notify,
                                  wip=wip,
                                  dest_branch=dest_branch,
                                  validate_certs=validate_certs,
@@ -1118,6 +1120,7 @@ class Project(object):
                       auto_topic=False,
                       draft=False,
                       private=False,
+                      notify=None,
                       wip=False,
                       dest_branch=None,
                       validate_certs=True,
@@ -1174,6 +1177,8 @@ class Project(object):
 
     opts = ['r=%s' % p for p in people[0]]
     opts += ['cc=%s' % p for p in people[1]]
+    if notify:
+      opts += ['notify=' + notify]
     if private:
       opts += ['private']
     if wip:

subcmds/upload.py

@@ -150,6 +150,9 @@ Gerrit Code Review:  https://www.gerritcodereview.com/
     p.add_option('-d', '--draft',
                  action='store_true', dest='draft', default=False,
                  help='If specified, upload as a draft.')
+    p.add_option('--ne', '--no-emails',
+                 action='store_false', dest='notify', default=True,
+                 help='If specified, do not send emails on upload.')
     p.add_option('-p', '--private',
                  action='store_true', dest='private', default=False,
                  help='If specified, upload as a private change.')
@@ -391,6 +394,7 @@ Gerrit Code Review:  https://www.gerritcodereview.com/
                                auto_topic=opt.auto_topic,
                                draft=opt.draft,
                                private=opt.private,
+                               notify=None if opt.notify else 'NONE',
                                wip=opt.wip,
                                dest_branch=destination,
                                validate_certs=opt.validate_certs,