I want to update the comments in the sensor_msgs/NavSatFix message.
This update is a clarification which arose in the NMEA GPS driver
review:

 http://ros.org/wiki/nmea_gps_driver/Reviews/2012-03-05_API_Review

It should not break anything, but I hate to commit a change to
sensor_msgs without a regression test.

Unfortunately, I can't figure out how to build common_msgs. I checked
out a copy and made my change. Here's the way I tried to build it
(without success):

 $ roscd sensor_msgs
 $ mkdir build
 $ cd build
 $ cmake ..
-- The C compiler identification is GNU
-- The CXX compiler identification is GNU
-- Check for working C compiler: /usr/bin/gcc
-- Check for working C compiler: /usr/bin/gcc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
CMake Error at CMakeLists.txt:2 (catkin_project):
  Unknown CMake command "catkin_project".


CMake Warning (dev) in CMakeLists.txt:
  No cmake_minimum_required command is present.  A line of code such as

    cmake_minimum_required(VERSION 2.8)

  should be added at the top of the file.  The version specified may be lower
  if you wish to support older CMake versions for this project.  For more
  information run "cmake --help-policy CMP0000".
This warning is for project developers.  Use -Wno-dev to suppress it.

-- Configuring incomplete, errors occurred!

Here is the change:

Index: msg/NavSatFix.msg
===================================================================
--- msg/NavSatFix.msg	(revision 38984)
+++ msg/NavSatFix.msg	(working copy)
@@ -2,7 +2,14 @@
 #
 # Specified using the WGS 84 reference ellipsoid

-# Header specifies ROS time and frame of reference for this fix.
+# header.stamp specifies the ROS time for this measurement (the
+#        corresponding satellite time may be reported using the
+#        sensor_msgs/TimeReference message).
+#
+# header.frame_id is the frame of reference reported by the satellite
+#        receiver, usually the location of the antenna.  This is a
+#        Euclidean frame relative to the vehicle, not a reference
+#        ellipsoid.
 Header header

 # satellite fix status information

Can someone tell me how to build common_msgs in Fuerte?

Should I commit this change, anyway? It should be safe.
-- 
 joq