workingfilectx: add backgroundclose as a kwarg to write()

This is necessary because some callers in merge.py pass backgroundclose=True
when writing.

As with previous changes in this series, this should be a no-op.

mercurial/context.py

@@ -1892,9 +1892,10 b' class workingfilectx(committablefilectx)'
         """wraps unlink for a repo's working directory"""
         self._repo.wvfs.unlinkpath(self._path, ignoremissing=ignoremissing)
 
-    def write(self, data, flags):
+    def write(self, data, flags, backgroundclose=False):
         """wraps repo.wwrite"""
-        self._repo.wwrite(self._path, data, flags)
+        self._repo.wwrite(self._path, data, flags,
+                          backgroundclose=backgroundclose)
 
     def setflags(self, l, x):
         self._repo.wvfs.setflags(self._path, l, x)

mercurial/merge.py

@@ -1130,7 +1130,6 b' def batchget(repo, mctx, wctx, actions):'
     """
     verbose = repo.ui.verbose
     fctx = mctx.filectx
-    wwrite = repo.wwrite
     ui = repo.ui
     i = 0
     with repo.wvfs.backgroundclosing(ui, expectedcount=len(actions)):
@@ -1151,7 +1150,7 b' def batchget(repo, mctx, wctx, actions):'
 
             if repo.wvfs.isdir(f) and not repo.wvfs.islink(f):
                 repo.wvfs.removedirs(f)
-            wwrite(f, fctx(f).data(), flags, backgroundclose=True)
+            wctx[f].write(fctx(f).data(), flags, backgroundclose=True)
             if i == 100:
                 yield i, f
                 i = 0