Bug with encoder type inference

[toots]

def g() =
  s = single("foo")

  s = s

  enc = %ffmpeg(
    format="mkv",
    %audio(codec="aac"),
    %video(codec="aac")
  )

  output.file(fallible=true, enc, "/tmp/bla.mkv", s)

  (s, enc)
end

Gives:

g :
  () ->
  source('a) * format(audio=pcm(stereo), video=canvas) = <fun>

While:

def g() =
  s = single("foo")

  #s = s

  enc = %ffmpeg(
    format="mkv",
    %audio(codec="aac"),
    %video(codec="aac")
  )

  output.file(fallible=true, enc, "/tmp/bla.mkv", s)

  (s, enc)
end

Gives, as expected:

g :
  () ->
  source(audio=pcm(stereo), video=canvas) * format(audio=pcm(stereo), video=canvas) = <fun>