tests: show that adding an already included path still calls narrow_widen()

This patch adds tests demonstrating that we still go to the server in
non-ellipses widening when we have that path already on the client and there is
nothing new to download.

The next patch will try to make client side logic smart and not go to the server
if we don't need to download anything.

Differential Revision: https://phab.mercurial-scm.org/D5182

tests/test-narrow-widen-no-ellipsis.t

@@ -140,6 +140,17 b' added upstream revisions.'
   $ hg id -n
   2
 
+Test that extending already included files should not call narrow_widen
+wireprotocol command
+
+  $ hg tracked --addinclude widest/f
+  comparing with ssh://user@dummy/master
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 0 changesets with 0 changes to 0 files
+
 Pull down the newly added upstream revision.
 
   $ hg pull