fix: prevent hash concatenation from causing hash collisions

Author: louisscruz

lib/index.js

@@ -30,7 +30,9 @@ function getTmpname (filename) {
   return filename + '.' +
     MurmurHash3(__filename)
       .hash(String(process.pid))
+      .hash('\0')
       .hash(String(threadId))
+      .hash('\0')
       .hash(String(++invocations))
       .result()
 }