Hide lines from the output about changing mode

These don't really add value for developers

Author: alex

pip/req/req_install.py

@@ -903,6 +903,7 @@ def _filter_install(self, line):
                 r'^\s*Skipping implicit fixer: ',
                 r'^\s*(warning: )?no previously-included (files|directories) ',
                 r'^\s*warning: no files found matching \'.*\'',
+                r'^\s*changing mode of',
                 # Not sure what this warning is, but it seems harmless:
                 r"^warning: manifest_maker: standard file '-c' not found$"]:
             if not line or re.search(regex, line.strip()):