[libraries][admin] Fixed editing

beat/web/libraries/admin.py

@@ -110,7 +110,10 @@ class LibraryModelForm(forms.ModelForm):
         # make sure we don't pass back a str field as 'file'
         if 'declaration_file' in self.data and \
                 isinstance(self.data['declaration_file'], six.string_types):
-            self.data['declaration_file'] = ContentFile(self.data['declaration_file'], name='unsaved')
+            mutable_data = self.data.copy()
+            mutable_data['declaration_file'] = ContentFile(self.data['declaration_file'], name='unsaved')
+            self.data = mutable_data
+
 
 
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