safe_while: Don't sleep() on the first attempt

This was causing unnecessary delays in several places

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>

teuthology/contextutil.py

@@ -119,6 +119,8 @@ class safe_while(object):
 
     def __call__(self):
         self.counter += 1
+        if self.counter == 1:
+            return True
         if self.counter > self.tries:
             error_msg = self._make_error_msg()
             if self._raise: