Conversion from markdown to markdown_github alters escaped pipe characters

[cacology]

Using pandoc 1.19.2.1 converting from pandoc flavored markdown to GitHub flavored markdown, an escaped pipe \| becomes a regular pipe |, which causes GitHub to make what should be a pipe character a table instead.

input file "example.md":

 This | is | a | pipe | table.
 
 This \| is \| a \| series \| of \| pipes.

command:

pandoc -f markdown -t markdown_github example.md

output:

This | is | a | pipe | table.

This | is | a | series | of | pipes.

expected output:

This | is | a | pipe | table.

This \| is \| a \| series \| of \| pipes.

My Haskell isn't great yet, but I think this might be an easy fix. If someone wants to try to point me at it, I'll try it, though I realize that may be more work than just fixing it...

Respectfully submitted,
-James

P.S. Probably not needed to fix the issue, but if you're curious as to why I need escaped pipes in my markdown, see: https://cacology.github.io/characters/ which uses pipes as the standard bibliographical notation to indicate line breaks. See also: http://www2.iath.virginia.edu/gants/Books/key.html or http://polaris.gseis.ucla.edu/jrichardson/dis237/Appendix%20A.htm

[jgm]

We just need to escape all | characters when the pipe_tables extension is enabled.

[jgm]

Look in src/Text/Pandoc/Writers/Markdown.hs, specifically at the escaping functions.

[jgm]

I also noticed that the new gfm output format (in dev pandoc) doesn't escape pipes. This will require changes in the underlying C library.