misc: remove requirement on python-magic

Python package changed between python3 and python2 on Debian
(python-magic is the pypi package python-magic, but python3-magic is the
pypi package file-magic :/)

setup.py

@@ -107,7 +107,6 @@ setup(
     install_requires=[
         'authentic2',
         'Pillow',
-        'python-magic',
         'sorl-thumbnail',
     ],
     entry_points={

src/authentic2_cut/api_views.py

@@ -16,7 +16,6 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import base64
-import magic
 import uuid
 
 from django.core.files.base import ContentFile
@@ -36,7 +35,7 @@ from django_filters.rest_framework import FilterSet
 from authentic2_idp_oidc.utils import make_pairwise_reversible_sub
 from authentic2 import api_views
 
-from . import models
+from . import models, utils
 
 
 class Base64ImageField(serializers.FileField):
@@ -128,7 +127,7 @@ def validate_cut(self, request, uuid):
                     'max-size': max_size,
                 })
             accepted_mime_types = _get_cut_validation_accepted_mime_types()
-            mime_type = magic.from_buffer(content.read(10000), mime=True)
+            mime_type = utils.mime_type_from_buffer(content.read(10000))
             if mime_type not in accepted_mime_types:
                 errors.append({
                     'code': 'justificatifs-bad-format',

src/authentic2_cut/utils.py

@@ -1,5 +1,7 @@
 # -*- coding: utf-8 -*-
 
+import magic
+
 from django.contrib.contenttypes.models import ContentType
 from django.contrib.auth import get_user_model
 from django_rbac.utils import get_ou_model, get_role_model, get_operation, get_permission_model
@@ -239,3 +241,10 @@ def update_roles():
     handle_ou(ou_territoire, **vars())
     for ou in OU.objects.exclude(slug__in=['usagers', 'territoire']):
         handle_ou(**vars())
+
+
+def mime_type_from_buffer(buf):
+    if hasattr(magic, 'from_buffer'):
+        return magic.from_buffer(buf, mime=True)
+    else:
+        return magic.detect_from_content(buf).mime_type

src/authentic2_cut/views.py

@@ -15,7 +15,6 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-import magic
 from contextlib import closing
 
 from django.utils.timezone import now
@@ -34,7 +33,7 @@ from authentic2 import hooks
 from authentic2.utils import redirect
 
 from .custom_settings import CORE_ATTRIBUTES
-from . import models, forms, tables
+from . import models, forms, tables, utils
 
 
 class EditCoreView(EditProfile):
@@ -272,7 +271,7 @@ def validation_attachment(request, pk, filename):
         raise PermissionDenied
     attachment = models.ValidationRequestAttachment.objects.get(pk=pk)
     attachment.image.open()
-    mime_type = magic.from_buffer(attachment.image.read(10000), mime=True)
+    mime_type = utils.mime_type_from_buffer(attachment.image.read(10000))
     attachment.image.open()
     return HttpResponse(attachment.image, content_type=mime_type)
 

tox.ini

@@ -39,6 +39,8 @@ deps =
   # dependency constraints for authentic
   py2: django-appconf<1.0.4
   py2: django-filter<2
+  py2: python-magic
+  py3: file-magic
   drf34: djangorestframework>=3.4,<3.4.1
   drf39: djangorestframework>=3.9.2,<3.10
   dj111: django<2.0