slapos.proxy: tests: do not wait for fixed time for external proxy to be started.

Also remove trailing whitespaces.

slapos/tests/slapproxy/__init__.py

@@ -32,6 +32,7 @@ import ConfigParser
 import os
 import logging
 import shutil
+import socket
 import subprocess
 import tempfile
 import time
@@ -41,6 +42,7 @@ from xml_marshaller.xml_marshaller import loads, dumps
 
 import slapos.proxy
 import slapos.proxy.views as views
+import slapos.slap
 import slapos.slap.slap
 
 import sqlite3
@@ -867,6 +869,8 @@ class TestMultiMasterSupport(MasterMixin):
     self.external_proxy_port = 8281
     self.external_master_url = 'http://%s:%s' % (self.external_proxy_host, self.external_proxy_port)
     self.external_computer_id = 'external_computer'
+    self.external_proxy_slap = slapos.slap.slap()
+    self.external_proxy_slap.initializeConnection(self.external_master_url)
 
     super(TestMultiMasterSupport, self).setUp()
 
@@ -900,9 +904,16 @@ database_uri = %(tempdir)s/lib/external_proxy.db
     # XXX use current dev version, not standard one installed through package
     self.external_proxy_process = subprocess.Popen(['slapos', 'proxy', 'start', '--cfg', self.external_slapproxy_configuration_file_location ])
     # Wait a bit for proxy to be started
-    time.sleep(0.5)
-    self.external_proxy_slap = slapos.slap.slap()
-    self.external_proxy_slap.initializeConnection(self.external_master_url)
+    attempts = 0
+    while (attempts < 20):
+      try:
+        self.external_proxy_slap._connection_helper.GET('/')
+      except slapos.slap.NotFoundError:
+        break
+      except socket.error:
+        attempts = attempts + 1
+        time.sleep(0.1)
+
 
   def createSlapOSConfigurationFile(self):
     """