Complete pull request is here: https://github.com/opscode-cookbooks/nginx/pull/123
According to the documentation the default is on, but if we default to nil, and wrap the value in the config file in a conditional, we can ensure we don't trigger a restart just from updating this cookbook.
Thanks for the tip. I've updated the pull request branch with a fix.
Not sure if it is an expected workflow, but I've just changed the state to "fix provided" to get the ticket reviewed again.
Merged in cfed86f
Released in 1.8.0