makebuildserver: make copy_caches_from_host do rsync like fdroid build

This rsync hung because of an SSH unknown key prompt.  Since this is just
the vm host sshing to the vm guest, it is not essential to check the host
keys.

fdroidserver/build.py

@@ -100,6 +100,7 @@ def build_server(app, build, vcs, build_dir, output_dir, log_dir, force):
         # Helper to copy the contents of a directory to the server...
         def send_dir(path):
             logging.debug("rsyncing " + path + " to " + ftp.getcwd())
+            # TODO this should move to `vagrant rsync` from >= v1.5
             try:
                 subprocess.check_output(['rsync', '--recursive', '--perms', '--links', '--quiet', '--rsh=' +
                                          'ssh -o StrictHostKeyChecking=no' +

makebuildserver

@@ -553,10 +553,16 @@ def main():
         for d in ('.m2', '.gradle/caches', '.gradle/wrapper', '.pip_download_cache'):
             fullpath = os.path.join(os.getenv('HOME'), d)
             if os.path.isdir(fullpath):
-                # TODO newer versions of vagrant provide `vagrant rsync`
+                ssh_command = ' '.join('ssh -i {0} -p {1}'.format(key, port),
+                                       '-o StrictHostKeyChecking=no',
+                                       '-o UserKnownHostsFile=/dev/null',
+                                       '-o LogLevel=FATAL',
+                                       '-o IdentitiesOnly=yes',
+                                       '-o PasswordAuthentication=no')
+                # TODO vagrant 1.5+ provides `vagrant rsync`
                 run_via_vagrant_ssh(v, ['cd ~ && test -d', d, '|| mkdir -p', d])
                 subprocess.call(['rsync', '-axv', '--progress', '--delete', '-e',
-                                 'ssh -i {0} -p {1} -oIdentitiesOnly=yes'.format(key, port),
+                                 ssh_command,
                                  fullpath + '/',
                                  user + '@' + hostname + ':~/' + d + '/'])