[libcalamares] The script namespace is actually a dict

Use dict methods, in particular d.get(k, v), to retrieve
the pretty_name() function (or None if it isn't there).
Using getattr() on a dict will not return values in the
dict.

src/libcalamares/PythonHelper.cpp

@@ -233,7 +233,7 @@ Helper::~Helper()
 {}
 
 
-boost::python::object
+boost::python::dict
 Helper::createCleanNamespace()
 {
     // To make sure we run each script with a clean namespace, we only fetch the

src/libcalamares/PythonHelper.h

@@ -51,7 +51,7 @@ public:
     explicit Helper( QObject* parent = nullptr );
     virtual ~Helper();
 
-    boost::python::object createCleanNamespace();
+    boost::python::dict createCleanNamespace();
 
     QString handleLastError();
 

src/libcalamares/PythonJob.cpp

@@ -296,7 +296,7 @@ PythonJob::exec()
 
     try
     {
-        bp::object scriptNamespace = helper()->createCleanNamespace();
+        bp::dict scriptNamespace = helper()->createCleanNamespace();
 
         bp::object calamaresModule = bp::import( "libcalamares" );
         bp::dict calamaresNamespace = bp::extract< bp::dict >( calamaresModule.attr( "__dict__" ) );
@@ -310,7 +310,7 @@ PythonJob::exec()
                                            scriptNamespace );
 
         bp::object entryPoint = scriptNamespace[ "run" ];
-        bp::object prettyNameFunc = bp::getattr(scriptNamespace, "pretty_name", bp::object());
+        bp::object prettyNameFunc = scriptNamespace.get("pretty_name", bp::object());
 
         cDebug() << "Job file" << scriptFI.absoluteFilePath();
         if ( !prettyNameFunc.is_none() )