shelve: attempt to make merge labels more helpful

Differential Revision: https://phab.mercurial-scm.org/D12024

mercurial/shelve.py

@@ -1000,7 +1000,11 b' def _rebaserestoredcommit('
         stats = merge.graft(
             repo,
             shelvectx,
-            labels=[b'working-copy', b'shelve'],
+            labels=[
+                b'working-copy',
+                b'shelved change',
+                b'parent of shelved change',
+            ],
             keepconflictparent=True,
         )
         if stats.unresolvedcount:

tests/test-shelve.t

@@ -423,7 +423,7 b' ensure that we have a merge with unresol'
    c
   +=======
   +a
-  +>>>>>>> shelve:       203c9f771d2b - shelve: changes to: [mq]: second.patch
+  +>>>>>>> shelved change: 203c9f771d2b - shelve: changes to: [mq]: second.patch
   diff --git a/b/b b/b.rename/b
   rename from b/b
   rename to b.rename/b

tests/test-shelve2.t

@@ -257,7 +257,7 b' unshelve and conflicts with tracked and '
   g
   =======
   f
-  >>>>>>> shelve:       aef214a5229c - shelve: changes to: commit stuff
+  >>>>>>> shelved change: aef214a5229c - shelve: changes to: commit stuff
   $ cat f.orig
   g
   $ hg unshelve --abort -t false
@@ -299,7 +299,7 b' unshelve and conflicts with tracked and '
   g
   =======
   f
-  >>>>>>> shelve:       aef214a5229c - shelve: changes to: commit stuff
+  >>>>>>> shelved change: aef214a5229c - shelve: changes to: commit stuff
   $ cat f.orig
   g
 
@@ -990,5 +990,5 b' Demonstrate that the labels are correct '
   this is in wdir, conflicts with shelve
   =======
   this will be shelved
-  >>>>>>> shelve:       9c072a2163db - shelve: changes to: r0
+  >>>>>>> shelved change: 9c072a2163db - shelve: changes to: r0
   $ cd ..