create_package_and_install properly handles when a specifier is not set for a targeted package within setup.py (Azure#25719)

Author: scbedd

eng/tox/create_package_and_install.py

@@ -234,7 +234,7 @@ def build_and_discover_package(setuppy_path, dist_dir, target_setup, package_typ
                                 addition_necessary = False
 
                             # ...do we need to install the new version? if the existing specifier matches, we're fine
-                            if installed_pkgs[req_name] in req_specifier:
+                            if req_specifier is not None and installed_pkgs[req_name] in req_specifier:
                                 addition_necessary = False
 
                         if addition_necessary: