tests: introduce tests for grafting through renames

These cover all currently known cases of renames being grafted,
or changes being grafted through renames.

Right now, most of these cases are broken. Later patches in this series
will make them behave correctly.

The testcases heavily rely on each other, which would make it very difficult
to separate them and add them one-by-one for each case fixed by a patch.
Separating them should perhaps be a 4.1 task, if it doesn't slow down
the tests too much.

(Developed together with Pierre-Yves David)

tests/test-graft.t

@@ -842,3 +842,461 b' Graft to duplicate a commit twice'
   |/
   o  0
   
+Graft from behind a move or rename
+==================================
+
+NOTE: This is affected by issue5343, and will need updating when it's fixed
+
+Possible cases during a regular graft (when ca is between cta and c2):
+
+name | c1<-cta | cta<->ca | ca->c2
+A.0  |         |          |
+A.1  |    X    |          |
+A.2  |         |     X    |
+A.3  |         |          |   X
+A.4  |    X    |     X    |
+A.5  |    X    |          |   X
+A.6  |         |     X    |   X
+A.7  |    X    |     X    |   X
+
+A.0 is trivial, and doesn't need copy tracking.
+For A.1, a forward rename is recorded in the c1 pass, to be followed later.
+In A.2, the rename is recorded in the c2 pass and followed backwards.
+A.3 is recorded in the c2 pass as a forward rename to be duplicated on target.
+In A.4, both passes of checkcopies record incomplete renames, which are
+then joined in mergecopies to record a rename to be followed.
+In A.5 and A.7, the c1 pass records an incomplete rename, while the c2 pass
+records an incomplete divergence. The incomplete rename is then joined to the
+appropriate side of the incomplete divergence, and the result is recorded as a
+divergence. The code doesn't distinguish at all between these two cases, since
+the end result of them is the same: an incomplete divergence joined with an
+incomplete rename into a divergence.
+Finally, A.6 records a divergence entirely in the c2 pass.
+
+A.4 has a degenerate case a<-b<-a->a, where checkcopies isn't needed at all.
+A.5 has a special case a<-b<-b->a, which is treated like a<-b->a in a merge.
+A.6 has a special case a<-a<-b->a. Here, checkcopies will find a spurious
+incomplete divergence, which is in fact complete. This is handled later in
+mergecopies.
+A.7 has 4 special cases: a<-b<-a->b (the "ping-pong" case), a<-b<-c->b,
+a<-b<-a->c and a<-b<-c->a. Of these, only the "ping-pong" case is interesting,
+the others are fairly trivial (a<-b<-c->b and a<-b<-a->c proceed like the base
+case, a<-b<-c->a is treated the same as a<-b<-b->a).
+
+f5a therefore tests the "ping-pong" rename case, where a file is renamed to the
+same name on both branches, then the rename is backed out on one branch, and
+the backout is grafted to the other branch. This creates a challenging rename
+sequence of a<-b<-a->b in the graft target, topological CA, graft CA and graft
+source, respectively. Since rename detection will run on the c1 side for such a
+sequence (as for technical reasons, we split the c1 and c2 sides not at the
+graft CA, but rather at the topological CA), it will pick up a false rename,
+and cause a spurious merge conflict. This false rename is always exactly the
+reverse of the true rename that would be detected on the c2 side, so we can
+correct for it by detecting this condition and reversing as necessary.
+
+First, set up the repository with commits to be grafted
+
+  $ hg init ../graftmove
+  $ cd ../graftmove
+  $ echo c1a > f1a
+  $ echo c2a > f2a
+  $ echo c3a > f3a
+  $ echo c4a > f4a
+  $ echo c5a > f5a
+  $ hg ci -qAm A0
+  $ hg mv f1a f1b
+  $ hg mv f3a f3b
+  $ hg mv f5a f5b
+  $ hg ci -qAm B0
+  $ echo c1c > f1b
+  $ hg mv f2a f2c
+  $ hg mv f5b f5a
+  $ echo c5c > f5a
+  $ hg ci -qAm C0
+  $ hg mv f3b f3d
+  $ echo c4d > f4a
+  $ hg ci -qAm D0
+  $ hg log -G
+  @  changeset:   3:b69f5839d2d9
+  |  tag:         tip
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     D0
+  |
+  o  changeset:   2:f58c7e2b28fa
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     C0
+  |
+  o  changeset:   1:3d7bba921b5d
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     B0
+  |
+  o  changeset:   0:11f7a1b56675
+     user:        test
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     summary:     A0
+  
+
+Test the cases A.2 (f1x), A.3 (f2x) and a special case of A.6 (f5x) where the
+two renames actually converge to the same name (thus no actual divergence).
+
+  $ hg up -q 'desc("A0")'
+  $ HGEDITOR="echo C1 >" hg graft -r 'desc("C0")' --edit
+  grafting 2:f58c7e2b28fa "C0"
+  merging f5a
+  warning: conflicts while merging f5a! (edit, then use 'hg resolve --mark')
+  abort: unresolved conflicts, can't continue
+  (use 'hg resolve' and 'hg graft --continue')
+  [255]
+  $ hg resolve f5a -t ':other' # XXX work around failure
+  (no more unresolved files)
+  continue: hg graft --continue
+  $ hg graft --continue # XXX work around failure
+  grafting 2:f58c7e2b28fa "C0"
+  warning: can't find ancestor for 'f5a' copied from 'f5b'!
+  $ hg status --change .
+  M f5a
+  A f1b
+  A f2c
+  R f2a
+  $ hg cat f1a
+  c1a
+  $ hg cat f1b
+  c1c
+
+Test the cases A.0 (f4x) and A.6 (f3x)
+
+  $ HGEDITOR="echo D1 >" hg graft -r 'desc("D0")' --edit
+  grafting 3:b69f5839d2d9 "D0"
+  warning: can't find ancestor for 'f3d' copied from 'f3b'!
+
+Set up the repository for some further tests
+
+  $ hg up -q "min(desc("A0"))"
+  $ hg mv f1a f1e
+  $ echo c2e > f2a
+  $ hg mv f3a f3e
+  $ hg mv f4a f4e
+  $ hg mv f5a f5b
+  $ hg ci -qAm "E0"
+  $ hg log -G
+  @  changeset:   6:ebba59d1fb02
+  |  tag:         tip
+  |  parent:      0:11f7a1b56675
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     E0
+  |
+  | o  changeset:   5:573bb6b4b56d
+  | |  user:        test
+  | |  date:        Thu Jan 01 00:00:00 1970 +0000
+  | |  summary:     D1
+  | |
+  | o  changeset:   4:af23416e619b
+  |/   parent:      0:11f7a1b56675
+  |    user:        test
+  |    date:        Thu Jan 01 00:00:00 1970 +0000
+  |    summary:     C0
+  |
+  | o  changeset:   3:b69f5839d2d9
+  | |  user:        test
+  | |  date:        Thu Jan 01 00:00:00 1970 +0000
+  | |  summary:     D0
+  | |
+  | o  changeset:   2:f58c7e2b28fa
+  | |  user:        test
+  | |  date:        Thu Jan 01 00:00:00 1970 +0000
+  | |  summary:     C0
+  | |
+  | o  changeset:   1:3d7bba921b5d
+  |/   user:        test
+  |    date:        Thu Jan 01 00:00:00 1970 +0000
+  |    summary:     B0
+  |
+  o  changeset:   0:11f7a1b56675
+     user:        test
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     summary:     A0
+  
+
+Test the cases A.4 (f1x), the "ping-pong" special case of A.7 (f5x),
+and A.3 with a local content change to be preserved (f2x).
+
+  $ HGEDITOR="echo C2 >" hg graft -r 'desc("C0")' --edit
+  grafting 2:f58c7e2b28fa "C0"
+  other [graft] changed f1b which local [local] deleted
+  use (c)hanged version, leave (d)eleted, or leave (u)nresolved? u
+  merging f2a and f2c to f2c
+  abort: unresolved conflicts, can't continue
+  (use 'hg resolve' and 'hg graft --continue')
+  [255]
+  $ hg resolve f1b -t ':other' # XXX work around failure
+  (no more unresolved files)
+  continue: hg graft --continue
+  $ hg graft --continue # XXX work around failure
+  grafting 2:f58c7e2b28fa "C0"
+  grafting 4:af23416e619b "C0"
+  merging f2c
+  warning: can't find ancestor for 'f2c' copied from 'f2a'!
+
+Test the cases A.1 (f4x) and A.7 (f3x).
+
+  $ HGEDITOR="echo D2 >" hg graft -r 'desc("D0")' --edit
+  grafting 3:b69f5839d2d9 "D0"
+  merging f4e and f4a to f4e
+  warning: can't find ancestor for 'f3d' copied from 'f3b'!
+
+Check the results of the grafts tested
+
+  $ hg log -CGv --patch --git
+  @  changeset:   9:6d76b84e6e84
+  |  tag:         tip
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  files:       f3d f4e
+  |  description:
+  |  D2
+  |
+  |
+  |  diff --git a/f3d b/f3d
+  |  new file mode 100644
+  |  --- /dev/null
+  |  +++ b/f3d
+  |  @@ -0,0 +1,1 @@
+  |  +c3a
+  |  diff --git a/f4e b/f4e
+  |  --- a/f4e
+  |  +++ b/f4e
+  |  @@ -1,1 +1,1 @@
+  |  -c4a
+  |  +c4d
+  |
+  o  changeset:   8:3079ba7d03f0
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  description:
+  |  C0
+  |
+  |
+  |
+  o  changeset:   7:dc778749ee9a
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  files:       f1b f2a f2c f5a f5b
+  |  copies:      f2c (f2a) f5a (f5b)
+  |  description:
+  |  C0
+  |
+  |
+  |  diff --git a/f1b b/f1b
+  |  new file mode 100644
+  |  --- /dev/null
+  |  +++ b/f1b
+  |  @@ -0,0 +1,1 @@
+  |  +c1c
+  |  diff --git a/f2a b/f2c
+  |  rename from f2a
+  |  rename to f2c
+  |  diff --git a/f5b b/f5a
+  |  rename from f5b
+  |  rename to f5a
+  |  --- a/f5b
+  |  +++ b/f5a
+  |  @@ -1,1 +1,1 @@
+  |  -c5a
+  |  +c5c
+  |
+  o  changeset:   6:ebba59d1fb02
+  |  parent:      0:11f7a1b56675
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  files:       f1a f1e f2a f3a f3e f4a f4e f5a f5a.orig f5b
+  |  copies:      f1e (f1a) f3e (f3a) f4e (f4a) f5b (f5a)
+  |  description:
+  |  E0
+  |
+  |
+  |  diff --git a/f1a b/f1e
+  |  rename from f1a
+  |  rename to f1e
+  |  diff --git a/f2a b/f2a
+  |  --- a/f2a
+  |  +++ b/f2a
+  |  @@ -1,1 +1,1 @@
+  |  -c2a
+  |  +c2e
+  |  diff --git a/f3a b/f3e
+  |  rename from f3a
+  |  rename to f3e
+  |  diff --git a/f4a b/f4e
+  |  rename from f4a
+  |  rename to f4e
+  |  diff --git a/f5a.orig b/f5a.orig
+  |  new file mode 100644
+  |  --- /dev/null
+  |  +++ b/f5a.orig
+  |  @@ -0,0 +1,5 @@
+  |  +<<<<<<< local: 11f7a1b56675  - test: A0
+  |  +c5a
+  |  +=======
+  |  +c5c
+  |  +>>>>>>> graft: f58c7e2b28fa  - test: C0
+  |  diff --git a/f5a b/f5b
+  |  rename from f5a
+  |  rename to f5b
+  |
+  | o  changeset:   5:573bb6b4b56d
+  | |  user:        test
+  | |  date:        Thu Jan 01 00:00:00 1970 +0000
+  | |  files:       f3d f4a
+  | |  description:
+  | |  D1
+  | |
+  | |
+  | |  diff --git a/f3d b/f3d
+  | |  new file mode 100644
+  | |  --- /dev/null
+  | |  +++ b/f3d
+  | |  @@ -0,0 +1,1 @@
+  | |  +c3a
+  | |  diff --git a/f4a b/f4a
+  | |  --- a/f4a
+  | |  +++ b/f4a
+  | |  @@ -1,1 +1,1 @@
+  | |  -c4a
+  | |  +c4d
+  | |
+  | o  changeset:   4:af23416e619b
+  |/   parent:      0:11f7a1b56675
+  |    user:        test
+  |    date:        Thu Jan 01 00:00:00 1970 +0000
+  |    files:       f1b f2a f2c f5a
+  |    copies:      f2c (f2a)
+  |    description:
+  |    C0
+  |
+  |
+  |    diff --git a/f1b b/f1b
+  |    new file mode 100644
+  |    --- /dev/null
+  |    +++ b/f1b
+  |    @@ -0,0 +1,1 @@
+  |    +c1c
+  |    diff --git a/f2a b/f2c
+  |    rename from f2a
+  |    rename to f2c
+  |    diff --git a/f5a b/f5a
+  |    --- a/f5a
+  |    +++ b/f5a
+  |    @@ -1,1 +1,1 @@
+  |    -c5a
+  |    +c5c
+  |
+  | o  changeset:   3:b69f5839d2d9
+  | |  user:        test
+  | |  date:        Thu Jan 01 00:00:00 1970 +0000
+  | |  files:       f3b f3d f4a
+  | |  copies:      f3d (f3b)
+  | |  description:
+  | |  D0
+  | |
+  | |
+  | |  diff --git a/f3b b/f3d
+  | |  rename from f3b
+  | |  rename to f3d
+  | |  diff --git a/f4a b/f4a
+  | |  --- a/f4a
+  | |  +++ b/f4a
+  | |  @@ -1,1 +1,1 @@
+  | |  -c4a
+  | |  +c4d
+  | |
+  | o  changeset:   2:f58c7e2b28fa
+  | |  user:        test
+  | |  date:        Thu Jan 01 00:00:00 1970 +0000
+  | |  files:       f1b f2a f2c f5a f5b
+  | |  copies:      f2c (f2a) f5a (f5b)
+  | |  description:
+  | |  C0
+  | |
+  | |
+  | |  diff --git a/f1b b/f1b
+  | |  --- a/f1b
+  | |  +++ b/f1b
+  | |  @@ -1,1 +1,1 @@
+  | |  -c1a
+  | |  +c1c
+  | |  diff --git a/f2a b/f2c
+  | |  rename from f2a
+  | |  rename to f2c
+  | |  diff --git a/f5b b/f5a
+  | |  rename from f5b
+  | |  rename to f5a
+  | |  --- a/f5b
+  | |  +++ b/f5a
+  | |  @@ -1,1 +1,1 @@
+  | |  -c5a
+  | |  +c5c
+  | |
+  | o  changeset:   1:3d7bba921b5d
+  |/   user:        test
+  |    date:        Thu Jan 01 00:00:00 1970 +0000
+  |    files:       f1a f1b f3a f3b f5a f5b
+  |    copies:      f1b (f1a) f3b (f3a) f5b (f5a)
+  |    description:
+  |    B0
+  |
+  |
+  |    diff --git a/f1a b/f1b
+  |    rename from f1a
+  |    rename to f1b
+  |    diff --git a/f3a b/f3b
+  |    rename from f3a
+  |    rename to f3b
+  |    diff --git a/f5a b/f5b
+  |    rename from f5a
+  |    rename to f5b
+  |
+  o  changeset:   0:11f7a1b56675
+     user:        test
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     files:       f1a f2a f3a f4a f5a
+     description:
+     A0
+  
+  
+     diff --git a/f1a b/f1a
+     new file mode 100644
+     --- /dev/null
+     +++ b/f1a
+     @@ -0,0 +1,1 @@
+     +c1a
+     diff --git a/f2a b/f2a
+     new file mode 100644
+     --- /dev/null
+     +++ b/f2a
+     @@ -0,0 +1,1 @@
+     +c2a
+     diff --git a/f3a b/f3a
+     new file mode 100644
+     --- /dev/null
+     +++ b/f3a
+     @@ -0,0 +1,1 @@
+     +c3a
+     diff --git a/f4a b/f4a
+     new file mode 100644
+     --- /dev/null
+     +++ b/f4a
+     @@ -0,0 +1,1 @@
+     +c4a
+     diff --git a/f5a b/f5a
+     new file mode 100644
+     --- /dev/null
+     +++ b/f5a
+     @@ -0,0 +1,1 @@
+     +c5a
+  
+  $ hg cat f2c
+  c2e