PartAttachment attachment file is actually required!

InvenTree/part/migrations/0028_auto_20190518_1627.py

@@ -0,0 +1,19 @@
+# Generated by Django 2.2 on 2019-05-18 06:27
+
+from django.db import migrations, models
+import part.models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('part', '0027_auto_20190518_1620'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='partattachment',
+            name='attachment',
+            field=models.FileField(help_text='Select file to attach', upload_to=part.models.attach_file),
+        ),
+    ]