Make so that admin editing a class will not unapprove it

When a class is edited, does a check for whether the person editing is
teaching the class; if not, don't call ClassSubject.propose()

esp/esp/program/controllers/classreg.py

@@ -104,6 +104,7 @@ def get_forms(self, reg_data, form_class=TeacherClassRegForm):
     def make_class_happen(self, cls, user, reg_form, resource_formset, restype_formset, editing=False):
         anchor_modified = self.set_class_data(cls, reg_form)
         self.update_class_sections(cls, int(reg_form.cleaned_data['num_sections']))
+
         #   If someone is editing the class, we assume they don't want to be
         #   added as a teacher if they aren't already one.
         if anchor_modified:
@@ -112,7 +113,11 @@ def make_class_happen(self, cls, user, reg_form, resource_formset, restype_forms
             if not editing:
                 self.associate_teacher_with_class(cls, user)
         self.add_rsrc_requests_to_class(cls, resource_formset, restype_formset)
-        cls.propose()
+
+        #   If someone is editing the class who isn't teaching it, don't unapprove it.
+        if user in cls.teachers():
+            cls.propose()
+
         cls.update_cache()
 
     def set_class_data(self, cls, reg_form):