testparseutil: escape backslash in docstring
This is funky. This inline Python code is part of a docstring, which
means the string is interpreted first. So any backslashes need double
escaping. So even though this is already a br'', we still need to escape.
Differential Revision: https://phab.mercurial-scm.org/D5842
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}