refactor(pre): use gitHead information from registry

lib/type/commits.js

@@ -4,10 +4,8 @@ var git = require('conventional-changelog/lib/git')
 
 var efh = require('../error').efh
 
-module.exports = function (cb) {
-  git.latestTag(efh(cb)(function (from) {
-    git.getCommits({from: from}, efh(cb)(function (commits) {
-      cb(null, commits)
-    }))
+module.exports = function (from, cb) {
+  git.getCommits({from: from}, efh(cb)(function (commits) {
+    cb(null, commits)
   }))
 }

lib/type/index.js

@@ -4,8 +4,8 @@ var analyze = require('./analyze')
 var commits = require('./commits')
 var efh = require('../error').efh
 
-module.exports = function (cb) {
-  commits(efh(cb)(function (commits) {
+module.exports = function (gitHead, cb) {
+  commits(gitHead, efh(cb)(function (commits) {
     cb(null, analyze(commits))
   }))
 }