bug#29074: 26.0; Cannot sent bug report in Emacs 26 pretest

[Eli Zaretskii]

> From: Glenn Morris <rgm@gnu.org>
> Date: Mon, 20 Nov 2017 16:40:19 -0500
> 
> A misconfigured system mailto handler is not an Emacs issue.
> 
> https://support.microsoft.com/en-us/help/312346/a-new-mail-message-window-does-not-open-when-you-click-a-mailto-link-o

For the record: that old article from MS Support is not relevant to
the issue at hand, because the default setting for handling the
'mailto' URLs was fixed on Windows years ago, and is out of the box
exactly like this article says.

The reason for the failure is most likely quoted strings "..." in the
Subject of the report.  This should be fixed in Emacs 26.1 and later.