debuginstall: strip double quotes from editorbin on Windows
The unconditional posix style shlex.split() prior to
94a1ff16f362 handled this.
This isn't mutually exclusive with stripping the quotes in util.findexe()- if
the editor can't be found, this command prints out the string, inside single
quotes.
#if no-windows no-osx
$ mkdir -p xdgconf/hg
$ echo '[ui]' > xdgconf/hg/hgrc
$ echo 'username = foobar' >> xdgconf/hg/hgrc
$ XDG_CONFIG_HOME="`pwd`/xdgconf" ; export XDG_CONFIG_HOME
$ unset HGRCPATH
$ hg config ui.username 2>/dev/null
foobar
#endif