It seems that it's simply impossible to run too many things in parallel over ADB on a single device. Really weird stuff happening, like completely unrelated shell calls using files created by other shell calls. Switch back to serial implementation.

lib/roles/device/support/channels.js

@@ -3,7 +3,7 @@ var syrup = require('syrup')
 var logger = require('../../../util/logger')
 var ChannelManager = require('../../../wire/channelmanager')
 
-module.exports = syrup()
+module.exports = syrup.serial()
   .define(function(options, router) {
     var log = logger.createLogger('device:support:channels')
     var channels = new ChannelManager()