repoview: add a test that access actual changeset data of `null`

Ideally, we would not trigger filtering here. However some work needs to happens
first.

Differential Revision: https://phab.mercurial-scm.org/D7482

tests/test-repo-filters-tiptoe.t

@@ -1,52 +1,59 b''
 ===================================
 Test repository filtering avoidance
 ===================================
 
 This test file is a bit special as he does not check feature, but performance related internal code path.
 
 Right now, filtering a repository comes with a cost that might be significant.
 Until this get better, ther are various operation that try hard not to trigger
 a filtering computation. This test file make sure we don't reintroduce code that trigger the filtering for these operation:
 
 Setup
 -----
   $ hg init test-repo
   $ cd test-repo
   $ echo "some line" > z
   $ echo a > a
   $ hg commit -Am a
   adding a
   adding z
   $ echo "in a" >> z
   $ echo b > b
   $ hg commit -Am b
   adding b
   $ echo "file" >> z
   $ echo c > c
   $ hg commit -Am c
   adding c
   $ hg rm a
   $ echo c1 > c
   $ hg add c
   c already tracked!
   $ echo d > d
   $ hg add d
   $ rm b
 
   $ cat << EOF >> $HGRCPATH
   > [devel]
   > debug.repo-filters = yes
   > [ui]
   > debug = yes
   > EOF
 
 
 tests
 -----
 
 Getting the node of `null`
 
   $ hg init test-repo
   $ cd test-repo
   $ hg log -r null -T "{node}\n"
   0000000000000000000000000000000000000000
+
+Getting basic changeset inforation about `null`
+
+  $ hg log -r null -T "{node}\n{date}\n"
+  debug.filters: computing revision filter for "visible"
+  0000000000000000000000000000000000000000
+  0.00