Add handling where argument is split at colon instead of equals.

src/manage/commands.py

@@ -373,7 +373,11 @@ def __init__(self, args, root=None):
                 seen_cmd = True
             elif a.startswith(("-", "/")):
                 a, sep, v = a.partition(":")
-                if not sep:
+                if sep:
+                    if "=" in a:
+                        a, sep, v_pre = a.partition("=")
+                        v = f"{v_pre}:{v}"
+                else:
                     a, sep, v = a.partition("=")
                 set_next = a.lstrip("-/").lower()
                 try:

tests/test_commands.py

@@ -81,3 +81,25 @@ def test_legacy_listpaths_command_help(assert_log, patched_installs):
     assert_log(
         assert_log.skip_until(r".*List command.+py list.+"),
     )
+
+
+def test_install_command_args():
+    # This is not meant to be exhaustive test of every possible option, but
+    # should cover all of the code paths in BaseCommand.__init__.
+    for args in [
+        ["-v", "-y"],
+        ["--v", "--y"],
+        ["/v", "/y"],
+    ]:
+        cmd = commands.InstallCommand(args)
+        assert cmd.log_level == logging.VERBOSE
+        assert not cmd.confirm
+
+    for args in [
+        ["--log", "C:\\LOG.txt"],
+        ["/log", "C:\\LOG.txt"],
+        ["--log:C:\\LOG.txt"],
+        ["--log=C:\\LOG.txt"],
+    ]:
+        cmd = commands.InstallCommand(args)
+        assert cmd.log_file == "C:\\LOG.txt"