location arg - should it be optional? fixes #4541.

compact / config: yes, should be optional (can get repo from BORG_REPO
environment variable)

some debug commands: rather not, have non-optional addtl. posargs

src/borg/archiver.py

@@ -2806,7 +2806,7 @@ class Archiver:
                                           formatter_class=argparse.RawDescriptionHelpFormatter,
                                           help='compact segment files / free space in repo')
         subparser.set_defaults(func=self.do_compact)
-        subparser.add_argument('location', metavar='REPOSITORY',
+        subparser.add_argument('location', metavar='REPOSITORY', nargs='?', default='',
                                type=location_validator(archive=False),
                                help='repository to compact')
         subparser.add_argument('--cleanup-commits', dest='cleanup_commits', action='store_true',
@@ -2843,7 +2843,7 @@ class Archiver:
         group.add_argument('-l', '--list', dest='list', action='store_true',
                                help='list the configuration of the repo')
 
-        subparser.add_argument('location', metavar='REPOSITORY',
+        subparser.add_argument('location', metavar='REPOSITORY', nargs='?', default='',
                                type=location_validator(archive=False, proto='file'),
                                help='repository to configure')
         subparser.add_argument('name', metavar='NAME', nargs='?',
@@ -3166,7 +3166,7 @@ class Archiver:
                                           formatter_class=argparse.RawDescriptionHelpFormatter,
                                           help='get object from repository (debug)')
         subparser.set_defaults(func=self.do_debug_get_obj)
-        subparser.add_argument('location', metavar='REPOSITORY', nargs='?', default='',
+        subparser.add_argument('location', metavar='REPOSITORY',
                                type=location_validator(archive=False),
                                help='repository to use')
         subparser.add_argument('id', metavar='ID', type=str,
@@ -3183,7 +3183,7 @@ class Archiver:
                                           formatter_class=argparse.RawDescriptionHelpFormatter,
                                           help='put object to repository (debug)')
         subparser.set_defaults(func=self.do_debug_put_obj)
-        subparser.add_argument('location', metavar='REPOSITORY', nargs='?', default='',
+        subparser.add_argument('location', metavar='REPOSITORY',
                                type=location_validator(archive=False),
                                help='repository to use')
         subparser.add_argument('paths', metavar='PATH', nargs='+', type=str,
@@ -3198,7 +3198,7 @@ class Archiver:
                                           formatter_class=argparse.RawDescriptionHelpFormatter,
                                           help='delete object from repository (debug)')
         subparser.set_defaults(func=self.do_debug_delete_obj)
-        subparser.add_argument('location', metavar='REPOSITORY', nargs='?', default='',
+        subparser.add_argument('location', metavar='REPOSITORY',
                                type=location_validator(archive=False),
                                help='repository to use')
         subparser.add_argument('ids', metavar='IDs', nargs='+', type=str,
@@ -3213,7 +3213,7 @@ class Archiver:
                                           formatter_class=argparse.RawDescriptionHelpFormatter,
                                           help='show refcount for object from repository (debug)')
         subparser.set_defaults(func=self.do_debug_refcount_obj)
-        subparser.add_argument('location', metavar='REPOSITORY', nargs='?', default='',
+        subparser.add_argument('location', metavar='REPOSITORY',
                                type=location_validator(archive=False),
                                help='repository to use')
         subparser.add_argument('ids', metavar='IDs', nargs='+', type=str,