build: delete unused code in igor.py

Author: nedbat

igor.py

@@ -8,7 +8,6 @@
 
 """
 
-import contextlib
 import datetime
 import glob
 import inspect
@@ -23,7 +22,6 @@
 import sysconfig
 import textwrap
 import types
-import warnings
 import zipfile
 
 try:
@@ -40,14 +38,6 @@
 PYPY = platform.python_implementation() == "PyPy"
 
 
-@contextlib.contextmanager
-def ignore_warnings():
-    """Context manager to ignore warning within the with statement."""
-    with warnings.catch_warnings():
-        warnings.simplefilter("ignore")
-        yield
-
-
 # $set_env.py: COVERAGE_IGOR_VERBOSE - More output from igor.py
 VERBOSITY = int(os.getenv("COVERAGE_IGOR_VERBOSE", "0"))