setup: display return code information about failed `hg` call
This help to understand what is going wrong when things goes wrong.
#!/usr/bin/env python3importerrnoimportosimportsysforfinsys.argv[1:]:try:print(f,'->',os.readlink(f))exceptOSErroraserr:iferr.errno!=errno.EINVAL:raiseprint(f,'->',f,'not a symlink')sys.exit(0)