chore(logging): downgrade redis.watch.conflict to warning level (#2307) r=@vladikoff

lib/redis/connection.js

@@ -68,7 +68,9 @@ module.exports = (log, client) => {
         .then(result => {
           isUpdating = false
           if (! result) {
-            log.error({ op: 'redis.watch.conflict', key })
+            // Really this isn't an error as such, it just indicates that
+            // this function is operating sanely in concurrent conditions.
+            log.warn({ op: 'redis.watch.conflict', key })
             throw error.unexpectedError()
           }
         })

test/local/redis/connection.js

@@ -490,10 +490,11 @@ describe('redis/connection:', () => {
         assert.equal(redisMulti.execAsync.callCount, 1)
       })
 
-      it('called log.error correctly', () => {
-        assert.equal(log.error.callCount, 1)
-        assert.equal(log.error.args[0].length, 1)
-        assert.deepEqual(log.error.args[0][0], {
+      it('called log.warn correctly', () => {
+        assert.equal(log.error.callCount, 0)
+        assert.equal(log.warn.callCount, 1)
+        assert.equal(log.warn.args[0].length, 1)
+        assert.deepEqual(log.warn.args[0][0], {
           op: 'redis.watch.conflict',
           key: 'wibble'
         })

test/remote/redis_tests.js

@@ -10,7 +10,7 @@ const assert = require('insist')
 const config = require(`${ROOT_DIR}/config`).getProperties()
 const P = require(`${ROOT_DIR}/lib/promise`)
 
-const log = { info () {}, error () {} }
+const log = { info () {}, warn () {}, error () {} }
 
 const redis = require(`${ROOT_DIR}/lib/redis`)(Object.assign({}, config.redis, { enabled: true }), log)