test-copies: reinstall initial identical (empty) files for chained copied

This effectively back out changeset deeb215be337. Changeset deeb215be33 does not
really include a justification for its change and make mes uncomfortable. I have
been thinking about it and they are two options:

- either having empty/full files does not make a difference, and deeb215be337 is
  a gratuitous changes.

- either having empty/full files do make a difference and deeb215be33 silently
  change the test coverage. In such situation if we want the "not empty" case to
  be tested, we should add new cases to cover them

In practice, we know that the "file content did not change, but merge still need
to create a new filenode" case exists (for example if merging result in similar
content but both parent of the file need to be recorded), and that such case are
easy to miss/mess-up in the tests. Having all the file using the same (empty)
content was done on purpose to increase the coverage of such corner case.

As a result I am reinstalling the previous test situation. To
increase the coverage of some case involving content-merge in
test-copies-chain-merge.t, we will add a new, dedicated, cases later in this
series, once various cleanup and test improvement have been set in place.

This changeset starts with reinstalling the previous situation as (1) it is more
fragile, so I am more confided getting it back in the initial situation, (2) I
have specific test further down the line that are base on these one.

The next changeset will slightly alter the test to use non-empty files for these
tests (with identical content). It should help to make the initial intent "merge file with identical
content" clearer. I am still using a two steps (backout, then change content)
approach to facilitate careful validation of the output change.

Doing so has a large impact on the output of the "copy info in changeset extra" variant
added in 5e72827dae1e (2 changesets after deeb215be33). It seems to highlight
various breakage when merge without content change are involved, this is a good
example of why we want to explicitly test theses cases. Because the different
-do- matters a lot.

Fixing the "copy info in changeset extra" is not a priority here. Because (1)
this changeset does not break anything, it only highlight that they were always
broken. (2) the only people using "copy info in changeset extra" do not have
merge.

Differential Revision: https://phab.mercurial-scm.org/D9587

tests/test-copies-chain-merge.t

@@ -50,9 +50,7 b' use git diff to see rename'
 
 Add some linear rename initialy
 
-  $ echo a > a
-  $ echo b > b
-  $ echo h > h
+  $ touch a b h
   $ hg ci -Am 'i-0 initial commit: a b h'
   adding a
   adding b
@@ -302,16 +300,17 b' Comparing with a merge with colliding re'
 
   $ hg up 'desc("a-2")'
   2 files updated, 0 files merged, 1 files removed, 0 files unresolved
-  $ hg merge 'desc("e-2")' --tool :union
-  merging f
-  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  $ hg merge 'desc("e-2")'
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved (no-changeset !)
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved (changeset !)
   (branch merge, don't forget to commit)
   $ hg ci -m 'mAEm-0 simple merge - one way'
   $ hg up 'desc("e-2")'
-  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
-  $ hg merge 'desc("a-2")' --tool :union
-  merging f
-  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved (no-changeset !)
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved (changeset !)
+  $ hg merge 'desc("a-2")'
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved (no-changeset !)
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved (changeset !)
   (branch merge, don't forget to commit)
   $ hg ci -m 'mEAm-0 simple merge - the other way'
   created new head
@@ -349,15 +348,16 b' Merge:'
   $ hg commit -m "f-2: rename i -> d"
   $ hg debugindex d
      rev linkrev nodeid       p1           p2
-       0       2 169be882533b 000000000000 000000000000 (no-changeset !)
-       0       2 b789fdd96dc2 000000000000 000000000000 (changeset !)
+       0       2 01c2f5eabdc4 000000000000 000000000000 (no-changeset !)
+       0       2 b80de5d13875 000000000000 000000000000 (changeset !)
        1       8 b004912a8510 000000000000 000000000000
-       2      22 4a067cf8965d 000000000000 000000000000 (no-changeset !)
-       2      22 fe6f8b4f507f 000000000000 000000000000 (changeset !)
+       2      22 c72365ee036f 000000000000 000000000000 (no-changeset !)
   $ hg up 'desc("b-1")'
-  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  3 files updated, 0 files merged, 0 files removed, 0 files unresolved (no-changeset !)
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved (changeset !)
   $ hg merge 'desc("f-2")'
-  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  1 files updated, 0 files merged, 1 files removed, 0 files unresolved (no-changeset !)
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved (changeset !)
   (branch merge, don't forget to commit)
   $ hg ci -m 'mBFm-0 simple merge - one way'
   $ hg up 'desc("f-2")'
@@ -394,7 +394,8 b" Unlike in the 'BD/DB' cases, an actual m"
 consider history and rename on both branch of the merge.
 
   $ hg up 'desc("i-2")'
-  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  3 files updated, 0 files merged, 0 files removed, 0 files unresolved (no-changeset !)
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved (changeset !)
   $ echo "some update" >> d
   $ hg commit -m "g-1: update d"
   created new head
@@ -448,16 +449,19 b' Note:'
   $ hg up 'desc("f-2")'
   1 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ hg merge 'desc("g-1")' --tool :union
-  merging d
-  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  merging d (no-changeset !)
+  0 files updated, 1 files merged, 0 files removed, 0 files unresolved (no-changeset !)
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved (changeset !)
   (branch merge, don't forget to commit)
   $ hg ci -m 'mFGm-0 simple merge - one way'
   created new head
   $ hg up 'desc("g-1")'
-  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved (no-changeset !)
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved (changeset !)
   $ hg merge 'desc("f-2")' --tool :union
-  merging d
-  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  merging d (no-changeset !)
+  0 files updated, 1 files merged, 1 files removed, 0 files unresolved (no-changeset !)
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved (changeset !)
   (branch merge, don't forget to commit)
   $ hg ci -m 'mGFm-0 simple merge - the other way'
   created new head
@@ -1120,15 +1124,15 b' The bugs makes recorded copy is differen'
   $ hg manifest --debug --rev 'desc("d-2")' | grep '644   d'
   b004912a8510032a0350a74daa2803dadfb00e12 644   d
   $ hg manifest --debug --rev 'desc("b-1")' | grep '644   d'
-  169be882533bc917905d46c0c951aa9a1e288dcf 644   d (no-changeset !)
-  b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644   d (changeset !)
+  01c2f5eabdc4ce2bdee42b5f86311955e6c8f573 644   d (no-changeset !)
+  b80de5d138758541c5f05265ad144ab9fa86d1db 644   d (changeset !)
   $ hg debugindex d | head -n 4
      rev linkrev nodeid       p1           p2
-       0       2 169be882533b 000000000000 000000000000 (no-changeset !)
-       0       2 b789fdd96dc2 000000000000 000000000000 (changeset !)
+       0       2 01c2f5eabdc4 000000000000 000000000000 (no-changeset !)
+       0       2 b80de5d13875 000000000000 000000000000 (changeset !)
        1       8 b004912a8510 000000000000 000000000000
-       2      22 4a067cf8965d 000000000000 000000000000 (no-changeset !)
-       2      22 fe6f8b4f507f 000000000000 000000000000 (changeset !)
+       2      22 c72365ee036f 000000000000 000000000000 (no-changeset !)
+       2      25 68d5bca9df05 b80de5d13875 000000000000 (changeset !)
 
 Log output should not include a merge commit as it did not happen
 
@@ -1179,34 +1183,30 b' Comparing with a merge with colliding re'
   
 #if no-changeset
   $ hg manifest --debug --rev 'desc("mAEm-0")' | grep '644   f'
-  c39c6083dad048d5138618a46f123e2f397f4f18 644   f
+  eb806e34ef6be4c264effd5933d31004ad15a793 644   f
   $ hg manifest --debug --rev 'desc("mEAm-0")' | grep '644   f'
-  a9a8bc3860c9d8fa5f2f7e6ea8d40498322737fd 644   f
+  eb806e34ef6be4c264effd5933d31004ad15a793 644   f
   $ hg manifest --debug --rev 'desc("a-2")' | grep '644   f'
-  263ea25e220aaeb7b9bac551c702037849aa75e8 644   f
+  0dd616bc7ab1a111921d95d76f69cda5c2ac539c 644   f
   $ hg manifest --debug --rev 'desc("e-2")' | grep '644   f'
-  71b9b7e73d973572ade6dd765477fcee6890e8b1 644   f
+  6da5a2eecb9c833f830b67a4972366d49a9a142c 644   f
   $ hg debugindex f
      rev linkrev nodeid       p1           p2
-       0       4 263ea25e220a 000000000000 000000000000
-       1      10 71b9b7e73d97 000000000000 000000000000
-       2      19 c39c6083dad0 263ea25e220a 71b9b7e73d97
-       3      20 a9a8bc3860c9 71b9b7e73d97 263ea25e220a
+       0       4 0dd616bc7ab1 000000000000 000000000000
+       1      10 6da5a2eecb9c 000000000000 000000000000
+       2      19 eb806e34ef6b 0dd616bc7ab1 6da5a2eecb9c
 #else
   $ hg manifest --debug --rev 'desc("mAEm-0")' | grep '644   f'
-  498e8799f49f9da1ca06bb2d6d4accf165c5b572 644   f
+  b80de5d138758541c5f05265ad144ab9fa86d1db 644   f
   $ hg manifest --debug --rev 'desc("mEAm-0")' | grep '644   f'
-  c5b506a7118667a38a9c9348a1f63b679e382f57 644   f
+  b80de5d138758541c5f05265ad144ab9fa86d1db 644   f
   $ hg manifest --debug --rev 'desc("a-2")' | grep '644   f'
-  b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644   f
+  b80de5d138758541c5f05265ad144ab9fa86d1db 644   f
   $ hg manifest --debug --rev 'desc("e-2")' | grep '644   f'
-  1e88685f5ddec574a34c70af492f95b6debc8741 644   f
+  b80de5d138758541c5f05265ad144ab9fa86d1db 644   f
   $ hg debugindex f
      rev linkrev nodeid       p1           p2
-       0       4 b789fdd96dc2 000000000000 000000000000
-       1      10 1e88685f5dde 000000000000 000000000000
-       2      19 498e8799f49f b789fdd96dc2 1e88685f5dde
-       3      20 c5b506a71186 1e88685f5dde b789fdd96dc2
+       0       4 b80de5d13875 000000000000 000000000000
 #endif
 
 # Here the filelog based implementation is not looking at the rename
@@ -1214,20 +1214,20 b' Comparing with a merge with colliding re'
 # based on works fine. We have different output.
 
   $ hg status --copies --rev 'desc("a-2")' --rev 'desc("mAEm-0")'
-  M f
-    b (no-filelog !)
+  M f (no-changeset !)
+    b (no-filelog no-changeset !)
   R b
   $ hg status --copies --rev 'desc("a-2")' --rev 'desc("mEAm-0")'
-  M f
-    b (no-filelog !)
+  M f (no-changeset !)
+    b (no-filelog no-changeset !)
   R b
   $ hg status --copies --rev 'desc("e-2")' --rev 'desc("mAEm-0")'
-  M f
-    d (no-filelog !)
+  M f (no-changeset !)
+    d (no-filelog no-changeset !)
   R d
   $ hg status --copies --rev 'desc("e-2")' --rev 'desc("mEAm-0")'
-  M f
-    d (no-filelog !)
+  M f (no-changeset !)
+    d (no-filelog no-changeset !)
   R d
   $ hg status --copies --rev 'desc("i-2")' --rev 'desc("a-2")'
   A f
@@ -1312,26 +1312,26 b' Merge:'
   R a
   R h
   $ hg status --copies --rev 'desc("b-1")' --rev 'desc("mBFm-0")'
-  M d
-    h (no-filelog !)
+  M d (no-changeset !)
+    h (no-filelog no-changeset !)
   R h
   $ hg status --copies --rev 'desc("f-2")' --rev 'desc("mBFm-0")'
   M b
   $ hg status --copies --rev 'desc("f-1")' --rev 'desc("mBFm-0")'
   M b
-  M d
-    i (no-filelog !)
+  M d (no-changeset !)
+    i (no-filelog no-changeset !)
   R i
   $ hg status --copies --rev 'desc("b-1")' --rev 'desc("mFBm-0")'
-  M d
-    h (no-filelog !)
+  M d (no-changeset !)
+    h (no-filelog no-changeset !)
   R h
   $ hg status --copies --rev 'desc("f-2")' --rev 'desc("mFBm-0")'
   M b
   $ hg status --copies --rev 'desc("f-1")' --rev 'desc("mFBm-0")'
   M b
-  M d
-    i (no-filelog !)
+  M d (no-changeset !)
+    i (no-filelog no-changeset !)
   R i
 
 #if no-changeset
@@ -1345,7 +1345,7 b' Merge:'
 #else
 BROKEN: `hg log --follow <file>` relies on filelog metadata to work
   $ hg log -Gfr 'desc("mBFm-0")' d
-  o  22 f-2: rename i -> d
+  o  2 i-2: c -move-> d
   |
   ~
 #endif
@@ -1361,7 +1361,7 b' BROKEN: `hg log --follow <file>` relies '
 #else
 BROKEN: `hg log --follow <file>` relies on filelog metadata to work
   $ hg log -Gfr 'desc("mFBm-0")' d
-  o  22 f-2: rename i -> d
+  o  2 i-2: c -move-> d
   |
   ~
 #endif
@@ -1509,15 +1509,15 b' In this case, the file hash from "f-2" i'
 Details on this hash ordering pick:
 
   $ hg manifest --debug 'desc("g-1")' | egrep 'd$'
-  f2b277c39e0d2bbac99d8aae075c0d8b5304d266 644   d (no-changeset !)
-  4ff57b4e8dceedb487e70e6965ea188a7c042cca 644   d (changeset !)
+  7bded9d9da1f7bf9bf7cbfb24fe1e6ccf68ec440 644   d (no-changeset !)
+  68d5bca9df0577b6bc2ea30ca724e13ead60da81 644   d (changeset !)
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("g-1")' d
   A d
     a (no-changeset no-compatibility !)
 
   $ hg manifest --debug 'desc("f-2")' | egrep 'd$'
-  4a067cf8965d1bfff130057ade26b44f580231be 644   d (no-changeset !)
-  fe6f8b4f507fe3eb524c527192a84920a4288dac 644   d (changeset !)
+  c72365ee036fca4fb27fd745459bfb6ea1ac6993 644   d (no-changeset !)
+  b80de5d138758541c5f05265ad144ab9fa86d1db 644   d (changeset !)
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("f-2")' d
   A d
     h (no-changeset no-compatibility !)
@@ -1526,13 +1526,14 b' Copy tracing data on the resulting merge'
 
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mFGm-0")'
   A d
-    h
+    h (no-filelog !)
+    a (filelog !)
   R a
   R h
   $ hg status --copies --rev 'desc("i-0")' --rev 'desc("mGFm-0")'
   A d
-    a (no-filelog !)
-    h (filelog !)
+    a (no-changeset !)
+    h (changeset !)
   R a
   R h
   $ hg status --copies --rev 'desc("f-2")' --rev 'desc("mFGm-0")'
@@ -1548,12 +1549,12 b' Copy tracing data on the resulting merge'
     i (no-filelog !)
   R i
   $ hg status --copies --rev 'desc("g-1")' --rev 'desc("mFGm-0")'
-  M d
-    h (no-filelog !)
+  M d (no-changeset !)
+    h (no-filelog no-changeset !)
   R h
   $ hg status --copies --rev 'desc("g-1")' --rev 'desc("mGFm-0")'
-  M d
-    h (no-filelog !)
+  M d (no-changeset !)
+    h (no-filelog no-changeset !)
   R h
 
 #if no-changeset
@@ -1575,12 +1576,8 b' Copy tracing data on the resulting merge'
 #else
 BROKEN: `hg log --follow <file>` relies on filelog metadata to work
   $ hg log -Gfr 'desc("mFGm-0")' d
-  o    28 mFGm-0 simple merge - one way
-  |\
-  | o  25 g-1: update d
-  | |
-  o |  22 f-2: rename i -> d
-  |/
+  o  25 g-1: update d
+  |
   o  2 i-2: c -move-> d
   |
   ~
@@ -1605,12 +1602,8 b' BROKEN: `hg log --follow <file>` relies '
 #else
 BROKEN: `hg log --follow <file>` relies on filelog metadata to work
   $ hg log -Gfr 'desc("mGFm-0")' d
-  o    29 mGFm-0 simple merge - the other way
-  |\
-  | o  25 g-1: update d
-  | |
-  o |  22 f-2: rename i -> d
-  |/
+  o  25 g-1: update d
+  |
   o  2 i-2: c -move-> d
   |
   ~