templater: don't normalize path separators to '/' when interacting with OS
`_readmapfile()` is about reading a map file from the file system, so
we shouldn't use our `util.normpath()`, which also normalizes `os.sep`
to '/'.
Differential Revision: https://phab.mercurial-scm.org/D8806
#require rust
$ rhg() {
> if [ -f "$RUNTESTDIR/../rust/target/debug/rhg" ]; then
> "$RUNTESTDIR/../rust/target/debug/rhg" "$@"
> else
> echo "skipped: Cannot find rhg. Try to run cargo build in rust/rhg."
> exit 80
> fi
> }
$ rhg unimplemented-command
[252]
$ rhg root
abort: no repository found in '$TESTTMP' (.hg not found)!
[255]
$ hg init repository
$ cd repository
$ rhg root
$TESTTMP/repository
$ rhg root > /dev/full
abort: No space left on device (os error 28)
[255]
$ rm -rf `pwd`
$ rhg root
abort: error getting current working directory: $ENOENT$
[255]