tests: avoid grafting the same change over and over

The test case added in a1381eea7c7d (graft: do not use `.remove` on a
smart set (regression), 2014-04-28) added a test case that grafted the
same change (renaming 'a' to 'b') three times over. It had description
"graft works on complex revset", but AFACT, all that it cared about
was that some ancestor of the working copy was in the set of revisions
to graft. So this patch changes the test to do that instead.

(I plan to later make it so that grafting these renames on top of each
won't create the empty commits they currently create.)

Differential Revision: https://phab.mercurial-scm.org/D7804

tests/test-graft.t

@@ -797,19 +797,12 b' All copies of a cset'
   summary:     2
   
 
-graft works on complex revset
+graft skips ancestors
 
-  $ hg graft 'origin(13) or destination(origin(13))'
+  $ hg graft 21 3
   skipping ancestor revision 21:7e61b508e709
-  skipping ancestor revision 22:3a4e92d81b97
-  skipping revision 2:5c095ad7e90f (already grafted to 22:3a4e92d81b97)
-  grafting 7:ef0ef43d49e7 "2"
-  warning: can't find ancestor for 'b' copied from 'a'!
-  grafting 13:7a4785234d87 "2"
-  warning: can't find ancestor for 'b' copied from 'a'!
-  grafting 19:9627f653b421 "2"
-  merging b
-  warning: can't find ancestor for 'b' copied from 'a'!
+  grafting 3:4c60f11aa304 "3"
+  merging b and c to c
 
 graft with --force (still doesn't graft merges)
 
@@ -828,15 +821,15 b" graft with --force (still doesn't graft "
 graft --force after backout
 
   $ echo abc > a
-  $ hg ci -m 28
-  $ hg backout 28
+  $ hg ci -m 26
+  $ hg backout 26
   reverting a
-  changeset 29:9d95e865b00c backs out changeset 28:cc20d29aec8d
-  $ hg graft 28
-  skipping ancestor revision 28:cc20d29aec8d
+  changeset 27:e25e17192dc4 backs out changeset 26:44f862488a35
+  $ hg graft 26
+  skipping ancestor revision 26:44f862488a35
   [255]
-  $ hg graft 28 --force
-  grafting 28:cc20d29aec8d "28"
+  $ hg graft 26 --force
+  grafting 26:44f862488a35 "26"
   merging a
   $ cat a
   abc
@@ -844,9 +837,9 b' graft --force after backout'
 graft --continue after --force
 
   $ echo def > a
-  $ hg ci -m 31
-  $ hg graft 28 --force --tool internal:fail
-  grafting 28:cc20d29aec8d "28"
+  $ hg ci -m 29
+  $ hg graft 26 --force --tool internal:fail
+  grafting 26:44f862488a35 "26"
   abort: unresolved conflicts, can't continue
   (use 'hg resolve' and 'hg graft --continue')
   [255]
@@ -859,7 +852,7 b' graft --continue after --force'
   (no more unresolved files)
   continue: hg graft --continue
   $ hg graft -c
-  grafting 28:cc20d29aec8d "28"
+  grafting 26:44f862488a35 "26"
   $ cat a
   abc
 
@@ -876,12 +869,12 b' but do some destructive editing of the r'
 
 Empty graft
 
-  $ hg up -qr 26
+  $ hg up -qr 24
   $ hg tag -f something
-  $ hg graft -qr 27
-  $ hg graft -f 27
-  grafting 27:17d42b8f5d50 "28"
-  note: graft of 27:17d42b8f5d50 created no changes to commit
+  $ hg graft -qr 25
+  $ hg graft -f 25
+  grafting 25:bd0c98709948 "26"
+  note: graft of 25:bd0c98709948 created no changes to commit
 
   $ cd ..