LESS "extend" syntax violates spaceAfterPropertyColon rule

[rumbu]

When I extend some class using this syntax, lesshint is recognizing it as violation of spaceAfterPropertyColon rule:

    &:extend(.chessboard);

The output is:

spaceAfterPropertyColon: Colon after property name should be followed by one space.

Pointing to after the colon character.

lesshint version - 6.3.6
Running as a gulp task.
I'd prefer not to ignore all the lines containing :extend nor disable spaceAfterPropertyColon rule.

[rumbu]

Thank you very much for the fix! ✔️