#015456: Problems with parsing emails that have "charset = " instead of "charset="

A part header that looks like:

--b1_f12f48b092f702bb16c4b012fb29d489
Content-Type: text/html; charset = "iso-8859-1"
Content-Transfer-Encoding: 8bit

is not parsed properly.

Operating System:
PHP Version: (please be specific, like '4.4.3' or '5.1.5')
Database and version:
Browser (and version):