Quoted text containing issue-like markdown creates incorrect links between issues

[ajf58]

Examples of this include SCons/scons#1, which contains a hash '#' followed by a number, which GitHub's markdown renderer parses as a link to another issue (see https://guides.github.com/features/mastering-markdown/). David Moody's suggestion from the scons-dev mailing list:

replace '#[number]' with 'choice [number]' in the text when they get reprocessed
Alternatively, we could insert a space character.