Added branch checkout corresponding to environment

index.js

 const processedArgs = cliargs(process.argv.slice(2));
 console.dir(processedArgs)
 
-var path = require('path')
+var path = require('path');
+const { isMaster } = require('cluster');
 // Serialize a set of functions that will execute to return a promises one after the other.
 // Will stop when any one fails.
 function any(iterable, continueOnFailure) {
       kill(serverPid)   
     }
     , 'use' : ()=>{
+      // use a certain named instance.
+      //  Eg : 
+        // 1) elxr use elixir
+        // 2) elxr use cihsr
+      // If environment is not specified defaults to development.
+        // 1) NODE=test elxr use elixir
 
       var runconfig = { NODE_ENV : process.env.NODE_ENV }  
       try { runconfig = Object.assign(runconfig, require('../run.js')) } catch(e) { }
       // console.log(process.env.cwd)
       fs.writeFileSync('./run.js', 'module.exports = ' + JSON.stringify(runconfig))
       
+      var checkoutMap = {
+        'development' : 'master',
+      }
+
+      // -b fails...
+      var performCheckout = (repo)=>{
+        return nodeShellExec('git', ['checkout', checkoutMap[runconfig.NODE_ENV] || runconfig.NODE_ENV], {
+          inherit : true, shell: true, 
+          cwd : repo
+        }).catch((e)=>{ console.error(e) }) 
+      }
+
       any(tasks).then(()=>{
         if(!processedArgs.runas) return op['runas']() 
 
             ]
           ) 
         }
-        return any(tasks).then(()=>{
+
+        return any(tasks.concat([
+          any(gitRepos.map((repo)=>performCheckout(repo))),
+          any(elevatedRunasRepos.map((repo)=>performCheckout(repo)))
+        ])
+        ).then(()=>{
           fs.writeFileSync('run.done', 'success')
         }).catch(()=>{
           fs.writeFileSync('run.done', 'error')