Do I need to add <build_depend> entries for pure Python packages?

edit

In the package.xml file we specify dependencies that we need at compile time for our package, e.g., as <build_depend>rospy</build_depend>.

As my Python package contains only Python code, that is not really compiled, do I actually have dependencies at compile time?

Or would it be enough to specify runtime dependencies for my example node?

Example (derived from this one):

<?xml version="1.0"?>
<package format="2">
  <name>beginner_tutorials</name>
  <version>0.1.0</version>
  <description>The beginner_tutorials package</description>

  <maintainer email="you@yourdomain.tld">Your Name</maintainer>
  <license>BSD</license>
  <url type="website">http://wiki.ros.org/beginner_tutorials</url>
  <author email="you@yourdomain.tld">Jane Doe</author>

  <buildtool_depend>catkin</buildtool_depend>

  <exec_depend>rospy</exec_depend>
  <exec_depend>std_msgs</exec_depend>

</package>

With a CMakeLists.txt, that I think, should go along these lines:

cmake_minimum_required(VERSION 2.8.3)
project(beginner_tutorials)

find_package(catkin REQUIRED COMPONENTS
  rospy
  std_msgs
)

catkin_package()

install(PROGRAMS
  scripts/listener.py
  DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
)