Imported Markdown inserts newlines

I am copying markdown from previously written files into new posts.

Much of my writing in markdown takes advantage of
the fact that md, like html, ignores linebreaks.
I typically write one sentence or one clause per line,
so that it is very easy to edit by
moving lines around to rearrange a sentence structure
or a paragraph.

Everywhere else,
this results in paragraphs when rendered.
Is there a way to
turn off the automatic line breaks I’m getting in the ghost editor,
so it doesn’t look like
I’m trying to achieve some
post-modernist poetry thing?