fileset: suppress EACCES while reading arbitrary paths via filectx API On Windows, EACCES is raised in place of EISDIR. This patch simply adds EACCES to the list of errors to be ignored since I think it's okay for filesets to treat inaccessible working-copy files as not existing.

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

sparse: add test showing `hg merge` is broken while using sparse extension This patch adds a test to demonstrate that `hg merge` is broken in some cases while using sparse extension. The case is when you have a file which is: * modified between current wdir parent and merge base * deleted between merge base and merge destination * excluded from sparse checkout Doing `hg merge` results in file not found error. Next patch will fix this. Differential Revision: https://phab.mercurial-scm.org/D3983