Georg's patch no longer applies to py3k.  I ported it, but the result is not functional.  It causes extra spaces during header generation, because it is there that email4/5 "deals" with "ignoring" spaces between encoded words by *adding* spaces when they are adjacent to non-encoded words.  (In general email4/5 compresses runs of whitespace into single spaces.)  I tried fixing that, but then ran in to the fact that header parsing/generation currently depends on the whitespace compression in order to handle the header folding cases.  So, the logic used for header parsing and generation in emai5 does not allow for an easy patch to fix this bug.  I'm deferring it to email6, where I an rewriting the header parser/generator.