Text copy issue when message is format=flowed

I found a problem when copying some message text to my clipboard. If I select a word by double-clicking and then copy it, there's a space added to end of the copied string.

This only happens if the following three conditions are met:
1. Message has Content-Type: text/plain; format=flowed
2. The word is at the end of a line
3. The word was selected by double-clicking it

It's reproducible with 1.0b10 on Mac OS X.

Here's an example message:

MIME-Version: 1.0
From: Somebody <foo@bar.com>
Subject: Re: The name?
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit

Hi Michael

More text here...

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When I now select "Michael" and copy it, my clipboard holds the string "Michael ".
I stumbled over this issue when I copy-and-pasted a password and it didn't work.