Bug#1003349: scour: autopkgtest needs update for new version of librsvg: DeprecationWarning: Rsvg.Handle.render_cairo is deprecated

[Simon McVittie <smcv@debian.org>]

Source: scour
Version: 0.37-2
Severity: important
X-Debbugs-Cc: debian-ci@lists.debian.org
Tags: experimental
User: debian-ci@lists.debian.org
Usertags: needs-update
Control: affects -1 src:librsvg

librsvg 2.52.x has deprecated Rsvg.Handle.render_cairo, which causes
scour's autopkgtest to fail (because a deprecation warning appears on stderr,
and by default autopkgtest considers a non-empty stderr to be a test failure).

librsvg is currently only in experimental, but it is likely to be uploaded
to unstable soon, at which point this will become RC.

There are three options for how to resolve this:

1. Stop using the deprecated function.
   The non-deprecated replacement is rsvg_handle_render_document(), which
   has different sizing behaviour that is hopefully easier to understand:
   see file:///usr/share/doc/librsvg2-dev/html/ch03.html for details.
2. Configure the test with the "allow-stderr" restriction so that output
   on stderr is not considered to be a test failure
3. Do both 1 and 2

Thanks,
    smcv