Add Aptsources822 lens for Deb822 style Apt sources

[jvalleroy]

We are using this lens in FreedomBox to add/remove "tor+" prefix to Apt sources URIs. Original commit: https://salsa.debian.org/freedombox-team/freedombox/-/commit/cd21c7f247135828e63379cc6d32a8edcb53a582

Closes: #297.

Signed-off-by: James Valleroy jvalleroy@mailbox.org

[georgehansper]

The lenses aptsources.aug and aptsources822.aug have overlapping definitions in the filter statement.
This results in an error because augeas can't determine which of the two lenses to apply. eg.

Error in /etc/apt/sources.list.d/man_examples.sources (mxfm_load)
Lenses @Aptsources822 and @Aptsources could be used to load this file

According to the man page for sources.list.d:

Filenames need to have either the extension .list or .sources depending on the contained format

This means that the existing lens should be limited to files named *.list, like this:

diff --git a/lenses/aptsources.aug b/lenses/aptsources.aug
index d7a6b3b1..e09634c7 100644
--- a/lenses/aptsources.aug
+++ b/lenses/aptsources.aug
@@ -60,7 +60,7 @@ module Aptsources =
 
   (* View: filter *)
   let filter = (incl "/etc/apt/sources.list")
-      . (incl "/etc/apt/sources.list.d/*")
+      . (incl "/etc/apt/sources.list.d/*.list")
       . Util.stdexcl

   let xfm = transform lns filter

Although this could be the subject of a separate PR, can I ask you to update this PR with the above change?

[georgehansper]

The lens works well, and thank you in particular for including tests

Just one point, if I may: Each "paragraph" must be separated by a non-comment blank line
This is handled correctly by this lens.

Multiple blank lines are permitted between "paragraphs", as long as there is at least one blank line
Zero or more leading and trailing blank lines are permitted
Currently, extraneous blank lines like this are not handled by this lens

Could you please update the lens to allow leading, trailing and repeated blank lines?