[Pkg-emacsen-addons] Bug#889849: muse-el: Make build reproducible

[Nicholas D Steeves]

Source: muse-el
Severity: normal

Muse-el has never been reproducible because documentation is generated
with embedded date stamp hashes using an application-specific method (
muse-batch-publish-files).  Resolving this bug requires one of two methods:

1) patch muse-el to generate the date stamp using a specific date
2) strip the date from the generated files

Resolving this bug will additionally allow a simple autopkgtest to be
written, where the documentation generated at build time will be
compared against a "known good" copy somewhere in the debian subdir.