Mercurial commit hook produces broken markup if the commit message is more than one line long

[kvas]

Environment

The issue affects mercurial commit hook installed on most repositories of hg.adblockplus.org.

How to reproduce

Create and push a commit that references an issue with multiline commit message.

Observed behaviour

The comment that is created in the issue has broken markup. See for example this comment in #4057.

Expected behaviour

Only the first line of the commit message should be used to render the link in the issue comment. If the second line is non-empty, an ellipsis ("...") should be added to the first line to indicate that there's a continuation (if the last character of the first line is a period, it should be replaced with the ellipsis instead). If the second line is empty, the first line is assumed to be a short summary of the whole commit message and the ellipsis should not be added.

[sebastian]

There are two kind of multiline commit messages:

1. Those that are wrapped to avoid long lines:

   Issue 1234 - Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur
   suscipit est urna, nec pretium arcu auctor nec. Nam hendrerit, arcu eu volutpat
   rhoncus, ipsum dui iaculis diam, quis volutpat diam diam nec dolor.
   

2. Those that have a second paragraph with additional information:

   Issue 1234 - Changed A to B
   
   Due to issue C with A it had to be changed to B for compatibility with D.
   

I think as for 1. we should replace the subsequent line with an ellipsis to indicate that there is more, otherwise it reads weird or the commit message might even be misinterpreted. However for 2. I think we can simply omit the subsequent lines without any indication. Do you agree, or do I overthink it?

[kvas]

You're right. Issue updated.

[abpbot]

A commit referencing this issue has landed:
​Fixes 4070 - Correctly handle multiline commit messages in the mercurial hook