Blanks before redefined heads not obeying grid in ConTeXt

Question

The following MWE in ConTeXt shows that if space is inserted before a chapter heading at the top of a page, it moves the contents of that page off the grid. Without the second argument to setuphead, the chapter heading sits on line 2; with it, I would like it to sit on line 3. Instead it sits between lines 3 and 4. Can someone advise how to achieve this?

\setuplayout[grid=yes]

\setuphead
    [chapter]
    [before={\blank[force,line]}]

\showgrid

\starttext

\startchapter[title={One}]
This is Chapter One.
\stopchapter

\stoptext

Answer 1

A non-elegant solution here: As \blank does not insert space if at the top of the page you can insert some material that will make it insert some. \mbox{} switches to horizontal mode and inserts an empty box (a typical LaTeX trick). That's already occupying a line. If you want to insert more space, \blank will work just fine.

\setuphead
    [chapter]
    [before={\mbox{}\blank[line]}]

\showgrid

\starttext

\startchapter[title={One}]
This is Chapter One.
\stopchapter

\startchapter[title={One}]
This is Chapter One.
\stopchapter

\stoptext