🐛 Fix detach error check (#190)

Added check for err.code
Added 5 attempts with backoff.

Author: blyork

lib/hdiutil.js

@@ -63,13 +63,17 @@ exports.attach = function (path, cb) {
 exports.detach = function (path, cb) {
   const args = ['detach', path]
 
-  util.sh('hdiutil', args, function (err) {
-    if (err && err.exitCode === 16 && /Resource busy/.test(err.stderr)) {
+  let attempts = 0
+  function attemptDetach (err) {
+    attempts += 1
+    if (err && (err.exitCode === 16 || err.code === 16) && /Resource busy/.test(err.stderr) && attempts <= 5) {
       setTimeout(function () {
-        util.sh('hdiutil', args, (err) => cb(err))
-      }, 1000)
+        util.sh('hdiutil', args, attemptDetach)
+      }, 1000 * Math.pow(2, attempts - 1))
     } else {
       cb(err)
     }
-  })
+  }
+
+  util.sh('hdiutil', args, attemptDetach)
 }