segfault on rfc2047-like subject

[Clint Adams]

The following message causes 0.92.7 to segfault.  I'd try with current
CVS, but it won't compile.

>From nowhere at example.com Thu Sep 16 21:42:32 2004
Subject: [Broken] =?ISO-8859-1?Q?Re=3A_=5BBroken=5D_=3D=3FISO-8859-1=3FQ=3F=3D5B?=
 =?ISO-8859-1?Q?Broken=3D5DBlah=3D20Foo=3DE4=3D20Bar=3D20Blah
 _?= =?ISO-8859-1?Q?Foo=3D3D28=3D5F=3F=3D_Bar=5F=5F=3F=3D_t=E4Blah?=
 =?ISO-8859-1?Q?Foo=E4t=29?=
X-Spam-Status: No, hits=0.0 required=5.0 tests=none autolearn=no version=2.64
Status: RO
Content-Length: 4
Lines: 1

Hi.