Here is patch (I wrote about it two weeks ago or so). During moving to guild I found one more limitation --- if called in REPL, (doctest "(foo)") do not restore previous state of interpreter. I am going to improve it and continuation master's advice is welcome.
Another issue is license. I did not signed paper about Guile (unfortunately, it is impossible to sign paper for all GNU project at once). Is it critical for such non-essensial part of Guile? Best regards