store only id for number builds projection

db.js

@@ -17,13 +17,13 @@ exports.init = function(dbPath, params, callback) {
 				descCreateDate: descCreateDate,
 				id: 1
 			}},
-			// note that's unordered projection (coz number is numeric)
-			// TODO: pick only id as value for that rare used projection
+			// note that's unordered projection (coz number is numeric),
+			// it also contains only id
 			{key: {
 				projectName: pickProjectName,
 				number: 1,
 				id: 1
-			}},
+			}, value: pickId},
 			{key: {
 				projectName: pickProjectName,
 				status: 1,

lib/notifier/index.js

@@ -33,6 +33,7 @@ exports.init = function(params, callback) {
 exports._getPrevBuild = function(build, callback) {
 	Steppy(
 		function() {
+			// get id of prev build
 			db.builds.find({
 				start: {
 					projectName: build.project.name,
@@ -41,6 +42,10 @@ exports._getPrevBuild = function(build, callback) {
 				limit: 1
 			}, this.slot());
 		},
+		function(err, builds) {
+			// get prev build by id
+			db.builds.find({start: {id: builds[0].id}}, this.slot());
+		},
 		function(err, builds) {
 			this.pass(builds[0]);
 		},