mergestate: inline `_resolve()` into `resolve()`

The caller is now trivial, so the indirection is pointless.

Differential Revision: https://phab.mercurial-scm.org/D11857

mercurial/mergestate.py

@@ -313,10 +313,10 b' class _mergestate_base(object):'
         """return extras stored with the mergestate for the given filename"""
         return self._stateextras[filename]
 
-    def _resolve(self, dfile, wctx):
-        """rerun merge process for file path `dfile`.
-        Returns the return value of merge obtained from filemerge._filemerge().
-        """
+    def resolve(self, dfile, wctx):
+        """run merge process for dfile
+
+        Returns the exit code of the merge."""
         if self[dfile] in (
             MERGE_RECORD_RESOLVED,
             LEGACY_RECORD_DRIVER_RESOLVED,
@@ -405,12 +405,6 b' class _mergestate_base(object):'
 
         return merge_ret
 
-    def resolve(self, dfile, wctx):
-        """run merge process for dfile
-
-        Returns the exit code of the merge."""
-        return self._resolve(dfile, wctx)
-
     def counts(self):
         """return counts for updated, merged and removed files in this
         session"""