Add config option for git clone URL

This commit adds a new config option 'git-url', where the
base URL can be specified to anything recognised by git-clone:
https://www.kernel.org/pub/software/scm/git/docs/git-clone.html#URLS

This is useful if the values provided by gerrit are incorrect, or if
you have access to a gerrit mirror closer to you.

Change-Id: I35ee5540aad2f27125ec15e6e933ac1ad3f3050e

examples/reference-gertty.yaml

@@ -32,6 +32,10 @@ servers:
 # Gertty will not modify them unless you tell it to, and even then the
 # normal git protections against losing work remain in place. [required]
 #    git-root: ~/git/
+# The URL to clone git repos. By default, <url>/p/<project> is used. For a list
+# of valid URLs, see:
+# https://www.kernel.org/pub/software/scm/git/docs/git-clone.html#URLS
+#    git-url: ssh://user@example.org:29418
 # The location of Gertty's sqlite database.  If you have more than one
 # server, you should specify a dburi for any additional servers.
 # By default a SQLite database called ~/.gertty.db is used.

gertty/config.py

@@ -46,6 +46,7 @@ class ConfigSchema(object):
               'ssl-ca-path': str,
               'dburi': str,
               v.Required('git-root'): str,
+              'git-url': str,
               'log-file': str,
               'socket': str,
               'auth-type': str,
@@ -177,6 +178,10 @@ class Config(object):
             # And this is to allow Git callouts
             os.environ['GIT_SSL_CAINFO'] = self.ssl_ca_path
         self.git_root = os.path.expanduser(server['git-root'])
+        git_url = server.get('git-url', self.url + 'p/')
+        if not git_url.endswith('/'):
+            git_url += '/'
+        self.git_url = git_url
         self.dburi = server.get('dburi',
                                 'sqlite:///' + os.path.expanduser('~/.gertty.db'))
         socket_path = server.get('socket', '~/.gertty.sock')

gertty/gitrepo.py

@@ -517,4 +517,4 @@ def get_repo(project_name, config):
     local_path = os.path.join(config.git_root, project_name)
     local_root = os.path.abspath(config.git_root)
     assert os.path.commonprefix((local_root, local_path)) == local_root
-    return Repo(config.url+'p/'+project_name, local_path)
+    return Repo(config.git_url + project_name, local_path)

gertty/sync.py

@@ -607,6 +607,7 @@ class SyncChangeTask(Task):
             for remote_commit, remote_revision in remote_change.get('revisions', {}).items():
                 revision = session.getRevisionByCommit(remote_commit)
                 # TODO: handle multiple parents
+                url = sync.app.config.git_url + change.project.name
                 if 'anonymous http' in remote_revision['fetch']:
                     ref = remote_revision['fetch']['anonymous http']['ref']
                     url = remote_revision['fetch']['anonymous http']['url']