Description of Problem:
When receiving email with an inline PGP (non PGP/MIME) message, evolution
only decodes it when the Content-Type header is set to 'text/plain;
charset="iso-8859-1"'. For example, 'Content-Type: text/plain;
charset="us-ascii"; format=flowed' doesn't work. Only changing us-ascii to
iso-8859-1 doesn't solve it, 'format=flowed' also blocks the decryption.

Steps to reproduce the problem:
1. Take an invalid inline PGP mail with charset='us-ascii'
2. edit it so that the Content-Type header reads 'Content-Type: text/plain;
charset="iso-8859-1"'
3. view in evolution
4. the decode happens

Actual Results:
No decoding

Expected Results:
Decoded message

How often does this happen? 
Always

Additional Information: