Note about using subdirectories to avoid bundling tests etc.

See #3954

.travis.yml

@@ -1,7 +1,17 @@
 language: ruby
-# XXX: Requires sudo because travis-ci apt-package-whitelist doesn't contain the
-# following packages: cvs darcs fossil texinfo
-sudo: required
+
+addons:
+  apt:
+    packages:
+    - bzr
+    - git
+    - mercurial
+    - subversion
+    - cvs
+    - darcs
+    - fossil
+    - texinfo
+
 before_install:
   - sudo apt-get -yq update
   - sudo apt-get -yq install bzr git mercurial subversion cvs darcs fossil texinfo

README.md

@@ -183,6 +183,10 @@ bundling external dependencies, but is otherwise fine with the defaults, it's
 recommended to use `:defaults` as the very first element of this list, which
 causes the default value shown above to be prepended to the specified file list.
 
+    Note that elisp in subdirectories is never included by default, so
+you might find it convenient to separate auxiliiary files such as tests into
+subdirectories to keep packaging simple.
+
 [git]: http://git-scm.com/
 [github]: https://github.com/
 [gitlab]: https://gitlab.com/