Use the new 'has_pure_modules()', 'has_ext_modules()', 'has_c_libraries()'
methods of Distribution instead of grovelling directly in self.distribution.
diff --git a/Lib/distutils/command/build.py b/Lib/distutils/command/build.py
index 97466fd..2da589a 100644
--- a/Lib/distutils/command/build.py
+++ b/Lib/distutils/command/build.py
@@ -80,18 +80,18 @@
 
         # Invoke the 'build_py' command to "build" pure Python modules
         # (ie. copy 'em into the build tree)
-        if self.distribution.packages or self.distribution.py_modules:
+        if self.distribution.has_pure_modules():
             self.run_peer ('build_py')
 
         # Build any standalone C libraries next -- they're most likely to
         # be needed by extension modules, so obviously have to be done
         # first!
-        if self.distribution.libraries:
+        if self.distribution.has_c_libraries():
             self.run_peer ('build_clib')
 
         # And now 'build_ext' -- compile extension modules and put them
         # into the build tree
-        if self.distribution.ext_modules:
+        if self.distribution.has_ext_modules():
             self.run_peer ('build_ext')
 
 # end class Build