sparse: add local files to temporaryfiles if they exist out of sparse We get the f1 from args if it's merge and check that whether that exists in sparse checkout or not. If that does not, we add that for merging. The error comes from very low-level where we try to read data of a working-filectx which does not exists in the working directory. It will be extremely ugly to plug in logic to update sparse copy with new file at such a low level. We already have logic related to updating the checkout with required files in calculateupdates() and let's handle this case there only. calculateupdates() call sparse.filterupdatesactions() and the logic is added into the latter function. To get the exact traceback, this patch can be backed out and test-sparse-merges.t can be run with ui.traceback=True. Differential Revision: https://phab.mercurial-scm.org/D4341

--- a/tests/test-sparse-merges.t	Tue Aug 21 15:09:22 2018 +0300
+++ b/tests/test-sparse-merges.t	Tue Aug 21 16:11:17 2018 +0300
@@ -172,10 +172,13 @@
   d
 
   $ hg merge
-  abort: $ENOENT$: $TESTTMP/mvtest/a
-  [255]
+  temporarily included 1 file(s) in the sparse checkout for merging
+  merging a and amove to amove
+  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
 
   $ hg up -C 4
+  cleaned up 1 temporarily added file(s) from the sparse checkout
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 
   $ hg merge