purge unnecessary setup.py copy_copyright function (#4950)

setup.py

@@ -1,5 +1,4 @@
 import os
-from shutil import copyfile
 import sys
 
 from setuptools import Command, setup
@@ -23,13 +22,6 @@ def run(self):
         pass
 
 
-def copy_copyright(cmd, directory):
-    # Copy the COPYRIGHT information into the package root
-    iris_build_dir = os.path.join(directory, "iris")
-    for fname in ["COPYING", "COPYING.LESSER"]:
-        copyfile(fname, os.path.join(iris_build_dir, fname))
-
-
 def build_std_names(cmd, directory):
     # Call out to tools/generate_std_names.py to build std_names module.
 
@@ -70,7 +62,7 @@ def run(self):
 
 custom_commands = {
     "develop": custom_cmd(develop_cmd, [build_std_names]),
-    "build_py": custom_cmd(build_py, [build_std_names, copy_copyright]),
+    "build_py": custom_cmd(build_py, [build_std_names]),
     "std_names": custom_cmd(
         BaseCommand,
         [build_std_names],