Sane scanner source paper source now defaults to blank.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

HISTORY.rst

@@ -159,6 +159,7 @@
   MAYAN_DEBUG.
 - Stricter defaults. CELERY_ALWAYS_EAGER to False, ALLOWED_HOSTS to ['127.0.0.1', 'localhost', '[::1]'].
 - New initialization command. Creates media/system and populates the SECRET_KEY and VERSION files.
+- Sane scanner source paper source now defaults to blank.
 
 2.7.3 (2017-09-11)
 ==================

mayan/apps/sources/migrations/0017_auto_20180510_2151.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.11 on 2018-05-10 21:51
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('sources', '0016_auto_20170630_2040'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='sanescanner',
+            name='source',
+            field=models.CharField(blank=True, choices=[('flatbed', 'Flatbed'), ('Automatic Document Feeder', 'Document feeder')], help_text='Selects the scan source (such as a document-feeder). If this option is not supported by your scanner, leave it blank.', max_length=32, null=True, verbose_name='Paper source'),
+        ),
+    ]

mayan/apps/sources/models.py

@@ -189,12 +189,10 @@ class SaneScanner(InteractiveSource):
         ), verbose_name=_('Resolution')
     )
     source = models.CharField(
-        blank=True, choices=SCANNER_SOURCE_CHOICES,
-        default=SCANNER_SOURCE_FLATBED, help_text=_(
+        blank=True, choices=SCANNER_SOURCE_CHOICES, help_text=_(
             'Selects the scan source (such as a document-feeder). If this '
             'option is not supported by your scanner, leave it blank.'
-        ), max_length=32,
-        verbose_name=_('Paper source')
+        ), max_length=32, null=True, verbose_name=_('Paper source')
     )
     adf_mode = models.CharField(
         blank=True, choices=SCANNER_ADF_MODE_CHOICES,