intermittent error: module-path-index-resolve: "self" index has no resolution

When running a file (with F5) in DrRacket, I sometimes get the following error:

../../../../.racket/snapshot/pkgs/drracket/drracket/private/module-language.rkt:482:8: module-path-index-resolve: "self" index has no resolution
  module path index: #<module-path-index:()>

I think this started after I upgraded from 6.6.0.5 to 6.7.0.1. Simply modifying the file (e.g. adding a space somewhere) and re-running the program seems to solve the issue.

I'm running a minimal racket install with an up-to-date main-distribution installed via raco pkg install main-distribution, except that I use an (updated) copy of the gui package with the https://github.com/racket/gui/pull/48 patch, but I don't see how that patch (which adds a preferences list for identifiers which behave like ellipses, and changes the indentation function accordingly) could cause the error message above.

Start by examining drracket/private/module-language.rkt at line 482 and reproduce the intermittent failure when running a file with F5. Compare behavior before and after modifying the file, and consider the reported upgrade and gui package patch as context; done means the self module-path index no longer fails to resolve.