failed diff generation email does not provide context for what failed

[Andrew Bennetts]

Yesterday I received this email:

"""
Date: Thu, 13 Jan 2011 00:34:53 -0000
From: <email address hidden>
To: Andrew Bennetts <email address hidden>
Subject: Launchpad error while generating the diff for a merge proposal
Message-Id: <email address hidden>
Reply-To: <email address hidden>
Precedence: bulk
X-Generated-By: Launchpad (canonical.com); Revision="12177";
        Instance="initZopeless config overlay"
X-Launchpad-Hash: d4f980e20aba0df527395dbabe9ca18be1191638

Launchpad encountered an error during the following operation: generating the diff for a merge proposal. The source branch has pending writes.
"""

This email lacks:

 * any hint as to which branch and merge proposal it is referring to
 * any useful X-Launchpad-* headers
 * any text or header explaining why I received this email
 * any hint about what I'm expected to do about this error
 * the standard signature block (“You received this because $reason. $link to primary object.")
 * possibly more

I think there's (at least) one systemic issue here: why is it possible for Launchpad to ever emit a mail without X-Launchpad-Message-Rationale? I would think the internal APIs should require a rationale, and/or the test suite should enforce this rule.

[Vincent Ladeuil (vila)]

+1 on spiv comment
kudos to https://launchpad.net/launchpad/+filebug allowing me to find the dupes