mise task arg doesn't respect double_dash=required

[prashantv]

I'm using args in a mise task, via the usage spec for more advanced features. Repro of the issue:

[tasks.echo]
usage = '''
arg "[file]" double_dash="required"
'''
run = 'echo hello {{ arg(name="file") }}'

I'm using double_dash="required", which from the docs says:

arg "" double_dash="required" # arg must be passed after a double dash (e.g. mycli -- file.txt)

However, the -- doesn't seem to be required:

$ mise run echo test
[echo] $ echo hello test
hello test

$ mise run echo -- test
[echo] $ echo hello test
hello test

I was expecting the first run without -- to return an error as there's no other flags defined.

mise version:

2025.7.21 macos-arm64 (2025-07-23)