Merge remote-tracking branch 'upstream/pull/2473'

diff --cc .travis.yml
index db9128412bc006d921684bd2764af1725293debf,fbb8b46ab0c2cb26e46464e9f784f0e984b3688e..b950b1e18e2cbf8083078758a08702d7493c267a
--- 1/.travis.yml
--- 2/.travis.yml
+++ b/.travis.yml
@@@ -9,8 -9,14 +9,11 @@@ addons
    apt:
      packages:
        - libarchive-dev
+       - libgd-dev
+       - libffi-dev
+       - libbz2-dev
  services:
    - memcached
 -env:
 -  global:
 -    - OSM_MEMCACHE_SERVERS="127.0.0.1"
  before_script:
    - sed -e 's/ IMMUTABLE / /' -e "/^--/d" db/structure.sql > db/structure.expected
    - psql -U postgres -c "CREATE DATABASE openstreetmap"