Make consent_to_research nullable

It should be nullable so we can tell whether someone has answered the
question already or not.

No real users have entered data into this column yet, so it’s fine to
wipe it.

migrations/versions/0277_consent_to_research_null.py

@@ -0,0 +1,71 @@
+"""
+
+Revision ID: 0277_consent_to_research_null
+Revises: 0266_user_folder_perms_table
+Create Date: 2019-03-01 13:47:15.720238
+
+"""
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+revision = '0277_consent_to_research_null'
+down_revision = '0266_user_folder_perms_table'
+
+
+def upgrade():
+    op.alter_column(
+        'services',
+        'consent_to_research',
+        existing_type=sa.BOOLEAN(),
+        nullable=True,
+        server_default=sa.null(),
+    )
+    op.alter_column(
+        'services_history',
+        'consent_to_research',
+        existing_type=sa.BOOLEAN(),
+        nullable=True,
+        server_default=sa.null(),
+    )
+    op.execute("""
+        UPDATE
+            services
+        SET
+            consent_to_research = null
+    """)
+    op.execute("""
+        UPDATE
+            services_history
+        SET
+            consent_to_research = null
+    """)
+
+
+def downgrade():
+    op.execute("""
+        UPDATE
+            services
+        SET
+            consent_to_research = false
+    """)
+    op.execute("""
+        UPDATE
+            services_history
+        SET
+            consent_to_research = false
+    """)
+    op.alter_column(
+        'services_history',
+        'consent_to_research',
+        existing_type=sa.BOOLEAN(),
+        nullable=False,
+        server_default=sa.false(),
+    )
+    op.alter_column(
+        'services',
+        'consent_to_research',
+        existing_type=sa.BOOLEAN(),
+        nullable=False,
+        server_default=sa.false(),
+    )