MNT: use string.Template for matplotlibrc.template

Switch to using `string.Template` instead of `%` formatting to
generate default matplotlibrc file.  This is to avoid having to escape
any old or new style format strings that we want to put into the default
matplotlibrc file.

Author: tacaswell

matplotlibrc.template

@@ -35,7 +35,7 @@
 # You can also deploy your own backend outside of matplotlib by
 # referring to the module name (which must be in the PYTHONPATH) as
 # 'module://my_backend'.
-backend      : %(backend)s
+backend      : $TEMPLATE_BACKEND
 
 # If you are using the Qt4Agg backend, you can choose here
 # to use the PyQt4 bindings or the newer PySide bindings to
@@ -338,12 +338,12 @@ backend      : %(backend)s
 # These values map to the scales:
 #    {'year': 365, 'month': 30, 'day': 1, 'hour': 1/24, 'minute': 1 / (24 * 60)}
 
-# date.autoformatter.year     : %%Y
-# date.autoformatter.month    : %%Y-%%m
-# date.autoformatter.day      : %%Y-%%m-%%d
-# date.autoformatter.hour     : %%H:%%M
-# date.autoformatter.minute   : %%H:%%M:%%S
-# date.autoformatter.second   : %%H:%%M:%%S.%%f
+# date.autoformatter.year     : %Y
+# date.autoformatter.month    : %Y-%m
+# date.autoformatter.day      : %Y-%m-%d
+# date.autoformatter.hour     : %H:%M
+# date.autoformatter.minute   : %H:%M:%S
+# date.autoformatter.second   : %H:%M:%S.%f
 
 ### TICKS
 # see http://matplotlib.org/api/axis_api.html#matplotlib.axis.Tick

setup.py

@@ -4,7 +4,7 @@
 """
 
 from __future__ import print_function, absolute_import
-
+from string import Template
 # This needs to be the very first thing to use distribute
 from distribute_setup import use_setuptools
 use_setuptools()
@@ -230,8 +230,9 @@ def run(self):
         default_backend = setupext.options['backend']
     with open('matplotlibrc.template') as fd:
         template = fd.read()
+    template = Template(template)
     with open('lib/matplotlib/mpl-data/matplotlibrc', 'w') as fd:
-        fd.write(template % {'backend': default_backend})
+        fd.write(template.safe_substitute(TEMPLATE_BACKEND=default_backend))
 
     # Build in verbose mode if requested
     if setupext.options['verbose']: