Configuration: allow usage of command-line scopes with environments (#14608)

Spack did not support usage of the `--config-scope` option in
combination with an environment: In `lib/spack/spack/main.py`,
`spack.config.command_line_scopes` is set equal to any config scopes
passed by the `--config-scope` option. However, this is done after
activating an environment. In the process of activating an environment,
the `spack.config.config` singleton is instantiated, so later setting of
`spack.config.command_line_scopes` is ignored.

This commit sets command line scopes before activating an environment to
ensure that they are included in the configuration.

Co-authored-by: Tim Fuller <tjfulle@sandia.gov>

lib/spack/spack/main.py

@@ -701,16 +701,16 @@ def main(argv=None):
         if stored_var_name in os.environ:
             os.environ[var] = os.environ[stored_var_name]
 
+    # make spack.config aware of any command line configuration scopes
+    if args.config_scopes:
+        spack.config.command_line_scopes = args.config_scopes
+
     # activate an environment if one was specified on the command line
     if not args.no_env:
         env = ev.find_environment(args)
         if env:
             ev.activate(env, args.use_env_repo)
 
-    # make spack.config aware of any command line configuration scopes
-    if args.config_scopes:
-        spack.config.command_line_scopes = args.config_scopes
-
     if args.print_shell_vars:
         print_setup_info(*args.print_shell_vars.split(','))
         return 0