message: Travis: Repeat apt-add-repository without relying on return value
  Recent failures on travis seem to point towards apt-add-repository
  not returning a non-null result when it fails. This is basically
  an attempt at a workaround for a presumed bug in apt-add-repository.
  Example of such a failure:
diff: @@ -91,8 +91,8 @@ before_install:
  - sudo apt-get update
  install:
  - - if [ -n "$PPA" ]; then travis_retry sudo add-apt-repository "$PPA" -y; fi
  - - if [ -n "$PPA2" ]; then travis_retry sudo add-apt-repository "$PPA2" -y; fi
  + - if [ -n "$PPA" ]; then for i in `seq 0 4`; do sudo add-apt-repository "$PPA" -y 2>&1|tee /dev/stderr|grep -q "imported" && break; sleep 30; done; fi
  + - if [ -n "$PPA2" ]; then for i in `seq 0 4`; do sudo add-apt-repository "$PPA2" -y 2>&1|tee /dev/stderr|grep -q "imported" && break; sleep 30; done; fi
  - if [ -n "$DPKG_ADD_ARCH" ]; then sudo dpkg --add-architecture "$DPKG_ADD_ARCH" ; fi
  - if [ -n "$PACKAGES" ]; then travis_retry sudo apt-get update; fi
  - if [ -n "$PACKAGES" ]; then travis_retry sudo apt-get install --no-install-recommends --no-upgrade -qq libdb4.8-dev libdb4.8++-dev $PACKAGES; fi
  