diff -r c6eb2118f44f -r 9db856446298 mercurial/sparse.py
--- a/mercurial/sparse.py	Tue Aug 21 15:09:22 2018 +0300
+++ b/mercurial/sparse.py	Tue Aug 21 16:11:17 2018 +0300
@@ -361,6 +361,11 @@
         elif file in wctx:
             prunedactions[file] = ('r', args, msg)
 
+        if branchmerge and type == mergemod.ACTION_MERGE:
+            f1, f2, fa, move, anc = args
+            if not sparsematch(f1):
+                temporaryfiles.append(f1)
+
     if len(temporaryfiles) > 0:
         repo.ui.status(_('temporarily included %d file(s) in the sparse '
                          'checkout for merging\n') % len(temporaryfiles))