Why the title tag '#' need a blank before the title on Notebook?

[muxuezi]

When I use IPython 3.2.1 Notebook, following h2 title tag is ok:

##Starting to Crawl

However, it's a mistake at IPython 4.0.0 Notebook, I had to add a blank to separate the ## tag and text.

## Starting to Crawl

Please excuse my ignorance. Is this necessary for any reason?
New version nbconvert was also failed when I build ipynb with Nikola blog generator

[minrk]

I believe this was a deliberate change in the marked javascript markdown implementation that we use.

[costerwi]

Surprised me too. Discussion here: markedjs/marked#201

[costerwi]

#276

[minrk]

@costerwi thanks, closing as duplicate.