Don't raise exception on missing man pages

The revert in Ia6cfbfe5b10a5b714fbb9f21ca61380aaf231638 actually
broke Sphinx 1.3.x support again. Try to fix it for real this
time by avoiding an exception on missing man_pages.

NOTE(dmllr): don't change dict while iterating over it, hopefully
this fixes the gating failure with python 3.5.x

Change-Id: I52d45fa0a0d42de690d3a492068f7bb03483a224
Related-Bug: 1379998

pbr/builddoc.py

@@ -141,7 +141,8 @@ def _sphinx_run(self, warnerrors):
             sphinx_config.init_values(warnings.warn)
         else:
             sphinx_config.init_values()
-        if self.builder == 'man' and len(sphinx_config.man_pages) == 0:
+        if self.builder == 'man' and len(
+                getattr(sphinx_config, 'man_pages', '')) == 0:
             return
         if self.sphinx_initialized:
             if sphinx_ver >= pkg_resources.parse_version('1.4.2'):

pbr/util.py

@@ -213,9 +213,9 @@ def cfg_to_args(path='setup.cfg', script_args=()):
     parser.read(path)
     config = {}
     for section in parser.sections():
-        config[section] = dict(parser.items(section))
-        for k in config[section]:
-            config[section][k.replace('-', '_')] = config[section].pop(k)
+        config[section] = dict()
+        for k, value in parser.items(section):
+            config[section][k.replace('-', '_')] = value
 
     # Run setup_hooks, if configured
     setup_hooks = has_get_option(config, 'global', 'setup_hooks')