copies: distinguish between merged and touched files during upgrade

This a filenode being different between p1, p2 and result does not necessarily
means a merges happens. For example p2 could be a strict newer version of p1, so
the p2 version is picked by the manifest merging, but then the file is manually
updated before the commit.

In this case the file should be detected as touched.

Differential Revision: https://phab.mercurial-scm.org/D10220

mercurial/metadata.py

@@ -326,8 +326,8 b' def _process_merge(p1_ctx, p2_ctx, ctx):'
     │ (None, Some) │     OR       │      ø       │🄼   Added     │OR 🅀 Salvaged │
     │              │🄹  Salvaged[2]│              │   (copied?)  │   (copied?)  │
     ├──────────────┼──────────────┼──────────────┼──────────────┼──────────────┤
-    │              │              │              │   🄾 Touched  │              │
-    │ (Some, Some) │🄺  No Changes │      ø       │OR 🅁 Salvaged │🄿   Merged    │
+    │              │              │              │   🄾 Touched  │   🄿 Merged   │
+    │ (Some, Some) │🄺  No Changes │      ø       │OR 🅁 Salvaged │OR 🅂 Touched  │
     │              │     [3]      │              │   (copied?)  │   (copied?)  │
     └──────────────┴──────────────┴──────────────┴──────────────┴──────────────┘
 
@@ -415,6 +415,7 b' def _process_merge(p1_ctx, p2_ctx, ctx):'
       nice bonus. However do not any of this yet.
     """
 
+    repo = ctx.repo()
     md = ChangingFiles()
 
     m = ctx.manifest()
@@ -462,8 +463,15 b' def _process_merge(p1_ctx, p2_ctx, ctx):'
                         # case 🄽 🄾 : touched
                         md.mark_touched(filename)
                 else:
-                    # case 🄿 : merged
-                    md.mark_merged(filename)
+                    fctx = repo.filectx(filename, fileid=d1[1][0])
+                    if fctx.p2().rev() == nullrev:
+                        # case 🅂
+                        # lets assume we can trust the file history. If the
+                        # filenode is not a merge, the file was not merged.
+                        md.mark_touched(filename)
+                    else:
+                        # case 🄿
+                        md.mark_merged(filename)
                 copy_candidates.append(filename)
             else:
                 # Impossible case, the post-merge file status cannot be None on

tests/test-copies-chain-merge.t

@@ -1965,25 +1965,13 b' We upgrade a repository that is not usin'
   ##### revision "mBF-change-m-0 merge with extra change - B side" #####
   1 sidedata entries
    entry-0014 size 14
-    '\x00\x00\x00\x01\x14\x00\x00\x00\x01\x00\x00\x00\x00d' (no-upgraded no-upgraded-parallel !)
-  touched    : d, ; (no-upgraded no-upgraded-parallel !)
-    '\x00\x00\x00\x01\x14\x00\x00\x00\x01\x00\x00\x00\x00d' (upgraded missing-correct-output !)
-  touched    : d, ; (upgraded missing-correct-output !)
-    '\x00\x00\x00\x01\x08\x00\x00\x00\x01\x00\x00\x00\x00d' (upgraded known-bad-output !)
-  merged     : d, ; (upgraded known-bad-output !)
-    '\x00\x00\x00\x01\x14\x00\x00\x00\x01\x00\x00\x00\x00d' (upgraded-parallel missing-correct-output !)
-  touched    : d, ; (upgraded-parallel missing-correct-output !)
-    '\x00\x00\x00\x01\x08\x00\x00\x00\x01\x00\x00\x00\x00d' (upgraded-parallel known-bad-output !)
-  merged     : d, ; (upgraded-parallel known-bad-output !)
+    '\x00\x00\x00\x01\x14\x00\x00\x00\x01\x00\x00\x00\x00d'
+  touched    : d, ;
   ##### revision "mFB-change-m-0 merge with extra change - B side" #####
   1 sidedata entries
    entry-0014 size 14
-    '\x00\x00\x00\x01\x14\x00\x00\x00\x01\x00\x00\x00\x00d' (no-upgraded no-upgraded-parallel !)
-  touched    : d, ; (no-upgraded no-upgraded-parallel !)
-    '\x00\x00\x00\x01\x08\x00\x00\x00\x01\x00\x00\x00\x00d' (upgraded-parallel known-bad-output !)
-  merged     : d, ; (upgraded-parallel known-bad-output !)
-    '\x00\x00\x00\x01\x08\x00\x00\x00\x01\x00\x00\x00\x00d' (upgraded known-bad-output !)
-  merged     : d, ; (upgraded known-bad-output !)
+    '\x00\x00\x00\x01\x14\x00\x00\x00\x01\x00\x00\x00\x00d'
+  touched    : d, ;
   ##### revision "mCB-change-m-0 merge explicitely revive deleted file - B side" #####
   1 sidedata entries
    entry-0014 size 14
@@ -3418,10 +3406,8 b' Merge:'
   A d
     h (filelog !)
     h (sidedata !)
-    a (upgraded known-bad-output !)
-    h (upgraded missing-correct-output !)
-    a (upgraded-parallel known-bad-output !)
-    h (upgraded-parallel missing-correct-output !)
+    h (upgraded !)
+    h (upgraded-parallel !)
     h (changeset !)
     h (compatibility !)
   A t