Put IOException message in wrapper, so we can deal with it.

Author: headius

core/src/main/java/org/jruby/util/io/PosixShim.java

@@ -412,7 +412,7 @@ public Channel open(String cwd, String path, ModeFlags flags, int perm, ClassLoa
         } catch (ResourceException.TooManySymlinks e) {
             errno = Errno.ELOOP;
         } catch (IOException e) {
-            throw new RuntimeException("Unhandled IOException", e);
+            throw new RuntimeException("Unhandled IOException" + e.getLocalizedMessage(), e);
         }
         return null;
     }