phases: introduce a performant efficient way to access revision in a set
This will be useful in the next changesets.
#!/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)