bsc: Allow to set the call-identity

Allow to set the cell-identity through the control interface
and add a small test for it.

Related: SYS#739
diff --git a/openbsc/tests/ctrl_test_runner.py b/openbsc/tests/ctrl_test_runner.py
index f32d1f8..d18e302 100644
--- a/openbsc/tests/ctrl_test_runner.py
+++ b/openbsc/tests/ctrl_test_runner.py
@@ -196,6 +196,26 @@
         self.assertEquals(r['mtype'], 'ERROR')
         self.assertEquals(r['error'], 'Input not within the range')
 
+    def testBtsCi(self):
+        r = self.do_get('bts.0.cell-identity')
+        self.assertEquals(r['mtype'], 'GET_REPLY')
+        self.assertEquals(r['var'], 'bts.0.cell-identity')
+        self.assertEquals(r['value'], '0')
+
+        r = self.do_set('bts.0.cell-identity', '23')
+        self.assertEquals(r['mtype'], 'SET_REPLY')
+        self.assertEquals(r['var'], 'bts.0.cell-identity')
+        self.assertEquals(r['value'], '23')
+
+        r = self.do_get('bts.0.cell-identity')
+        self.assertEquals(r['mtype'], 'GET_REPLY')
+        self.assertEquals(r['var'], 'bts.0.cell-identity')
+        self.assertEquals(r['value'], '23')
+
+        r = self.do_set('bts.0.cell-identity', '-1')
+        self.assertEquals(r['mtype'], 'ERROR')
+        self.assertEquals(r['error'], 'Input not within the range')
+
     def testTrxPowerRed(self):
         r = self.do_get('bts.0.trx.0.max-power-reduction')
         self.assertEquals(r['mtype'], 'GET_REPLY')