config: add a missing preparewrite() call
Thanks Yuya for pointing this out in D808.
Differential Revision: https://phab.mercurial-scm.org/D924
--- a/mercurial/config.py Tue Oct 03 16:59:17 2017 -0700
+++ b/mercurial/config.py Tue Oct 03 12:00:07 2017 -0700
@@ -177,6 +177,7 @@
if sections and section not in sections:
continue
if self.get(section, name) is not None:
+ self._data[section] = self._data[section].preparewrite()
del self._data[section][name]
self._unset.append((section, name))
continue