Make sql reporter score null when not set

Rather than storing a 0, allow the sql reporter to store Null if no
score is set.

Also rename the alembic.ini file to be as alembic expects since it
exists in its own directory path now.

Change-Id: I5c99cd0d10d3cab7af4029b106bcd8f6c0ccbd23

zuul/driver/sql/alembic_reporter/versions/1dd914d4a482_allow_score_to_be_null.py

@@ -0,0 +1,25 @@
+"""Allow score to be null
+
+Revision ID: 1dd914d4a482
+Revises: 4d3ebd7f06b9
+Create Date: 2017-03-28 08:09:32.908643
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '1dd914d4a482'
+down_revision = '4d3ebd7f06b9'
+branch_labels = None
+depends_on = None
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    op.alter_column('zuul_buildset', 'score', nullable=True,
+                    existing_type=sa.Integer)
+
+
+def downgrade():
+    raise Exception("Downgrades not supported")

zuul/driver/sql/sqlconnection.py

@@ -80,7 +80,7 @@ class SQLConnection(BaseConnection):
             sa.Column('change', sa.Integer, nullable=True),
             sa.Column('patchset', sa.Integer, nullable=True),
             sa.Column('ref', sa.String(255)),
-            sa.Column('score', sa.Integer),
+            sa.Column('score', sa.Integer, nullable=True),
             sa.Column('message', sa.TEXT()),
         )
 

zuul/driver/sql/sqlreporter.py

@@ -29,8 +29,7 @@ class SQLReporter(BaseReporter):
         super(SQLReporter, self).__init__(
             driver, connection, config)
         # TODO(jeblair): document this is stored as NULL if unspecified
-        # TODO(jhesketh): actually make this null in a followup change
-        self.result_score = config.get('score', 0)
+        self.result_score = config.get('score', None)
 
     def report(self, source, pipeline, item):
         """Create an entry into a database."""