merge: do the trivial resolution after updating sparse checkout

In merge, we do trivial resolution for files which were deleted on one side and
changed on other. When sparse extension in involved that file might not be
present in wdir and trivial resolution can lead to file not found error. This
patch make sure we updates the sparse checkout before doing the trivial
resolution.

This fixes the test failure demonstrated in previous patch.

Differential Revision: https://phab.mercurial-scm.org/D3984

mercurial/merge.py

@@ -1424,14 +1424,13 b' def calculateupdates(repo, wctx, mctx, a'
                 del actions[f]
         repo.ui.note(_('end of auction\n\n'))
 
-    _resolvetrivial(repo, wctx, mctx, ancestors[0], actions)
-
     if wctx.rev() is None:
         fractions = _forgetremoved(wctx, mctx, branchmerge)
         actions.update(fractions)
 
     prunedactions = sparse.filterupdatesactions(repo, wctx, mctx, branchmerge,
                                                 actions)
+    _resolvetrivial(repo, wctx, mctx, ancestors[0], actions)
 
     return prunedactions, diverge, renamedelete
 

tests/test-sparse-merges.t

@@ -112,5 +112,9 b' file is excluded from sparse checkout'
   a
 
   $ hg merge
-  abort: $ENOENT$: '$TESTTMP/ytest/d'
-  [255]
+  temporarily included 1 file(s) in the sparse checkout for merging
+  local [working copy] changed d which other [merge rev] deleted
+  use (c)hanged version, (d)elete, or leave (u)nresolved? u
+  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
+  use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
+  [1]