cmdutil: migrate previously missed instances to uipathfn

I seem to have missed these two instances in 15f63ac122ea (files:
respect ui.relative-paths, 2019-01-29) and 7068c6b0114b (revert:
respect ui.relative-paths, 2019-02-05).

Differential Revision: https://phab.mercurial-scm.org/D5915

mercurial/cmdutil.py

@@ -2193,7 +2193,7 b' def files(ui, ctx, m, fm, fmt, subrepos)'
                     ret = 0
             except error.LookupError:
                 ui.status(_("skipping missing subrepository: %s\n")
-                               % m.rel(subpath))
+                               % uipathfn(subpath))
 
     return ret
 
@@ -2825,7 +2825,7 b' def revert(ui, repo, ctx, parents, *pats'
                 for f in names:
                     if f.startswith(path_):
                         return
-                ui.warn("%s: %s\n" % (m.rel(path), msg))
+                ui.warn("%s: %s\n" % (uipathfn(path), msg))
 
             for abs in ctx.walk(matchmod.badmatch(m, badfn)):
                 if abs not in names: