py3: use byteskwargs in sparse.py

This removes several dozen failures in Python 3.

Differential Revision: https://phab.mercurial-scm.org/D1482

hgext/sparse.py

@@ -82,6 +82,7 b' from mercurial import ('
     extensions,
     hg,
     match as matchmod,
+    pycompat,
     registrar,
     sparse,
     util,
@@ -286,6 +287,7 b' def debugsparse(ui, repo, *pats, **opts)'
 
     Returns 0 if editing the sparse checkout succeeds.
     """
+    opts = pycompat.byteskwargs(opts)
     include = opts.get('include')
     exclude = opts.get('exclude')
     force = opts.get('force')