Start: Correct hash for thumbnail filename (py3)

Image file names need to be quoted before hashing to generate thumbnail file names. This is related to pull requests #4931 and #4972, so please refer to discussions therein. Only Python3 is supported, not Python2.

src/Mod/Start/StartPage/StartPage.py

@@ -109,14 +109,8 @@ def getInfo(filename):
             import gnomevfs
         except Exception:
             # alternative method
-            import hashlib,sys
-            if sys.version_info.major < 3:
-                import urllib
-                hashload = urllib.quote("file://"+path,safe=":/")
-            else:
-                import urllib.parse
-                hashload = bytes(urllib.parse.quote("file://"+path,safe=":/"),"ascii")
-            fhash = hashlib.md5(hashload).hexdigest()
+            import hashlib,urllib.parse
+            fhash = hashlib.md5(bytes(urllib.parse.quote("file://"+path,safe=":/"),"ascii")).hexdigest()
             thumb = os.path.join(os.path.expanduser("~"),".thumbnails","normal",fhash+".png")
         else:
             uri = gnomevfs.get_uri_from_local_path(path)