Add global --plus-config command arg

can now omit `--config` to get "normal" config, and use
`--plus-config` to add some tweaks

rattail/commands/core.py

@@ -201,6 +201,8 @@ Usage: {0.name} [options] <command> [command-options]
 Options:
   -c PATH, --config=PATH
                     Config path (may be specified more than once)
+  --plus-config=PATH
+                    Extra config to load *in addition to* the normal config
   -n, --no-init     Do not read any config files
   -P, --progress    Show progress indicators (where relevant)
   -R, --runas       Optional username to impersonate when running command
@@ -225,6 +227,9 @@ Commands:\n""".format(self))
 
         parser.add_argument('-c', '--config', action='append', dest='config_paths',
                             metavar='PATH')
+        parser.add_argument('--plus-config', action='append',
+                            dest='plus_config_paths', metavar='PATH',
+                            help="Extra config to load *in addition to* the normal config")
 
         # TODO: i think these aren't really being used in practice..?
         parser.add_argument('-n', '--no-init', action='store_true', default=False)
@@ -302,7 +307,8 @@ Commands:\n""".format(self))
 
         else: # otherwise we make a proper config, and maybe turn on versioning
             logging.basicConfig()
-            self.config = make_config(args.config_paths, extend=args.extend_config, versioning=False)
+            self.config = make_config(args.config_paths, plus_files=args.plus_config_paths,
+                                      extend=args.extend_config, versioning=False)
             if args.versioning:
                 configure_versioning(self.config, force=True)
             elif not args.no_versioning:

rattail/config.py

@@ -1537,11 +1537,28 @@ class ConfigExtension(object):
         """
 
 
-def make_config(files=None, usedb=None, preferdb=None, env=None, winsvc=None, extend=True, versioning=None):
+def make_config(
+        files=None,
+        plus_files=None,
+        usedb=None,
+        preferdb=None,
+        env=None,
+        winsvc=None,
+        extend=True,
+        versioning=None):
     """
     Returns a new config object, initialized with the given parameters and
     further modified by all registered config extensions.
 
+    :param files: Config path(s) to be loaded.  If not specified, then some
+       "default" behavior will be attempted.  This will check for env var
+       ``RATTAIL_CONFIG_FILES`` or fallback to system default paths.  Or
+       you can override all that by specifying some path(s) here.
+
+    :param plus_files: Additional config path(s) to be loaded.  You
+       may specify a "config tweak" file here, and leave ``files``
+       empty, to get "normal plus tweak" behavior.
+
     :param versioning: Controls whether or not the versioning system is
        configured with the new config object.  If ``True``, versioning will be
        configured.  If ``False`` then it will not be configured.  If ``None``
@@ -1570,6 +1587,11 @@ def make_config(files=None, usedb=None, preferdb=None, env=None, winsvc=None, ex
     elif isinstance(files, str):
         files = [files]
 
+    if plus_files:
+        if isinstance(plus_files, str):
+            plus_files = [plus_files]
+        files += plus_files
+
     # If making config for a Windows service, we must read the default config
     # file(s) first, and check it to see if there is an alternate config file
     # which should be considered the "root" file.  Normally we specify the root