diff --git a/addons/project/models/project.py b/addons/project/models/project.py
index 89fc9d5741c..3f1035dd06a 100644
--- a/addons/project/models/project.py
+++ b/addons/project/models/project.py
@@ -228,7 +228,9 @@ class Project(models.Model):
     def map_tasks(self, new_project_id):
         """ copy and map tasks from old to new project """
         tasks = self.env['project.task']
-        for task in self.tasks:
+        # We want to copy archived task, but do not propagate an active_test context key
+        task_ids = self.env['project.task'].with_context(active_test=False).search([('project_id', '=', self.id)]).ids
+        for task in self.env['project.task'].browse(task_ids):
             # preserve task name and stage, normally altered during copy
             defaults = {'stage_id': task.stage_id.id,
                         'name': task.name}
@@ -239,7 +241,6 @@ class Project(models.Model):
     def copy(self, default=None):
         if default is None:
             default = {}
-        self = self.with_context(active_test=False)
         if not default.get('name'):
             default['name'] = _("%s (copy)") % (self.name)
         project = super(Project, self).copy(default)