Fix dbrestore of sqlite database to like newlines

On Textfields that have line breaks, sqlite reports "unrecognized token"
because it doesn't keep the previous line in memory to be ammended by
the current line.

This pull requests implements a very simple logic to only send SQL
INSERT commands when the line finished with ");".

Close jazzband#238

dbbackup/db/sqlite.py

@@ -67,13 +67,25 @@ def restore_dump(self, dump):
         if not self.connection.is_usable():
             self.connection.connect()
         cursor = self.connection.cursor()
+        sql_command = b""
+        sql_is_complete = True
         for line in dump.readlines():
-            try:
-                cursor.execute(line.decode('UTF-8'))
-            except OperationalError as err:
-                warnings.warn("Error in db restore: {}".format(err))
-            except IntegrityError as err:
-                warnings.warn("Error in db restore: {}".format(err))
+            sql_command = sql_command + line
+            line_str = line.decode('UTF-8')
+            if line_str.startswith("INSERT") and not line_str.endswith(");\n"):
+                sql_is_complete = False
+                continue
+            if not sql_is_complete and line_str.endswith(");\n"):
+                sql_is_complete = True
+
+            if sql_is_complete:
+                try:
+                    cursor.execute(sql_command.decode('UTF-8'))
+                except OperationalError as err:
+                    warnings.warn("Error in db restore: {}".format(err))
+                except IntegrityError as err:
+                    warnings.warn("Error in db restore: {}".format(err))
+                sql_command = b""
 
 
 class SqliteCPConnector(BaseDBConnector):

dbbackup/tests/test_connectors/test_sqlite.py

@@ -6,7 +6,7 @@
 from django.utils.six import BytesIO
 
 from dbbackup.db.sqlite import SqliteConnector, SqliteCPConnector
-from dbbackup.tests.testapp.models import CharModel
+from dbbackup.tests.testapp.models import CharModel, TextModel
 
 
 class SqliteConnectorTest(TestCase):