Multiline environment specification broken

[maxwellmckinnon]

[testenv]
deps =
    pytest
    u: pylint

commands =
    u: pylint -E .
    s: pytest \
    -c tox.ini \
    --junit-prefix={envname} {posargs}

Breaks

ERROR: InvocationError for command could not find executable c

[maxwellmckinnon]

tox==3.14.5