fix issues with simultaneous configs and security jail on skfiddle

experimental/webtry/webtry.go

 package main
 
 import (
         "bytes"
         "crypto/md5"
         "database/sql"
         "encoding/base64"
         "encoding/binary"
         "encoding/json"
         "flag"
@@ skipping 930 matching lines @@
                         png, err := ioutil.ReadFile("../../../inout/" + hash + "_raster.png")
                         if err != nil {
                                 reportTryError(w, r, err, "Failed to open the raster-generated PNG.", hash)
                                 return
                         }
 
                         m.RasterImg = base64.StdEncoding.EncodeToString([]byte(png))
                 }
 
                 if request.GPU {
-                        png, err := ioutil.ReadFile("../../../inout/" + hash + "_GPU.png")
+                        png, err := ioutil.ReadFile("../../../inout/" + hash + "_gpu.png")
                         if err != nil {
                                 reportTryError(w, r, err, "Failed to open the GPU-generated PNG.", hash)
                                 return
                         }
 
                         m.GPUImg = base64.StdEncoding.EncodeToString([]byte(png))
                 }
 
                 resp, err := json.Marshal(m)
                 if err != nil {
@@ skipping 16 matching lines @@
         http.HandleFunc("/sources/", autogzip.HandleFunc(sourcesHandler))
 
         // Resources are served directly
         // TODO add support for caching/etags/gzip
         http.Handle("/res/", autogzip.Handle(http.FileServer(http.Dir("./"))))
 
         // TODO Break out /c/ as it's own handler.
         http.HandleFunc("/", autogzip.HandleFunc(mainHandler))
         glog.Fatal(http.ListenAndServe(*port, nil))
 }