Cell inserted in the table header row when it should not

[aleb]

Prerequisites

• Put an X between the brackets on this line if you have done all of the following:
  • Reproduced the problem in Safe Mode: http://flight-manual.atom.io/hacking-atom/sections/debugging/#using-safe-mode
  • Followed all applicable steps in the debugging guide: http://flight-manual.atom.io/hacking-atom/sections/debugging/
  • Checked the FAQs on the message board for common solutions: https://discuss.atom.io/c/faq
  • Checked that your issue isn't already filed: https://github.com/issues?utf8=✓&q=is%3Aissue+user%3Aatom
  • Checked that there is not already an Atom package that provides the described functionality: https://atom.io/packages

Description

Table in markdown file does not appear correct.

Steps to Reproduce

Create a test.md file with the following content:

| a | b | c |
 --- | --- | ---
a | a | a

Press ctrl+shift+m, notice a table with two rows appears, and the first row has 4 cells instead of 3, first cell being empty.

Expected behavior:
https://gist.github.com/aleb/f6ed33806ca5dcbee0434544887360dd

Actual behavior:

Reproduces how often: 100

Versions

$ atom --version
Atom : 1.18.0
Electron: 1.3.15
Chrome : 52.0.2743.82
Node : 6.5.0
$ apm --version
apm 1.18.1
npm 3.10.10
node 6.9.5 x64
python 2.7.10
git 2.14.1

[camilo-celis]

I have similar problem for a table along the lines:

| a | b | c |
|---|---|---|
| aa | aa | aa |
| bb | bb |      |

Actual behaviour