[pdal-commits] [PDAL/PDAL] c4b533: Update dockerfiles for alpine 3.9/pdal 1.9 (#2490)

[backporting[bot]]

  Branch: refs/heads/1.9-maintenance
  Home:   https://github.com/PDAL/PDAL
  Commit: c4b533d019d3b65ac3580a9db1659795dbe19647
      https://github.com/PDAL/PDAL/commit/c4b533d019d3b65ac3580a9db1659795dbe19647
  Author: backporting[bot] <backporting[bot]@users.noreply.github.com>
  Date:   2019-05-03 (Fri, 03 May 2019)

  Changed paths:
    M scripts/docker/alpine/Dockerfile
    M scripts/docker/alpine/Dockerfile.dependencies

  Log Message:
  -----------
  Update dockerfiles for alpine 3.9/pdal 1.9 (#2490)