fixup! Add support for escaping $ with $$

src/zc/buildout/buildout.py

@@ -54,6 +54,7 @@ import sys
 import tempfile
 import zc.buildout
 import zc.buildout.download
+from functools import partial
 
 PY3 = sys.version_info[0] == 3
 if PY3:
@@ -1537,10 +1538,12 @@ def _save_option(option, value, f):
 
 def _save_options(section, options, f):
     print_('[%s]' % section, file=f)
-    items = list(options.items())
-    items.sort()
-    for option, value in items:
-        _save_option(option, value, f)
+    if isinstance(options, Options):
+        get_option = partial(options.get, last=False)
+    else:
+        get_option = options.get
+    for option in sorted(options):
+        _save_option(option, get_option(option), f)
 
 def _default_globals():
     """Return a mapping of default and precomputed expressions.