release-post script breaks if there is a line after a header link

[evanlucas]

If there is a line after the <a id="6.3.1"></a> header link in node changelogs, the release-post script breaks

[lpinca]

The problem is in these two regex 1, 2. The second one does not match as there is a leading \n.
I think the beast approach to fix this is to trim the matched section.