mdbook watch doesn't build into build.build-dir

[bryfry]

Result: the output of the build process lands in the source folder at source/book instead of the expected destination directory. I was pulling my hair out trying to find out where it was writing to until I ran strace and caught it in the act of writing to the wrong directory. I also tried forcing this parameter in the book.toml with the same results.

Expected Result: Build output should go into the build.build-dir, just like build does.

Command: mdbook watch source --dest-dir /var/www/html/book

Running version: mdbook-v0.3.7-x86_64-unknown-linux-gnu

book.toml:

[book]
authors = ["alta3"]
language = "en"
multilingual = false
src = "."
title = "Alta3 Ansible Essentials"