cgal /usr/lib/x86_64-linux-gnu/cmake/CGAL/CGAL_CoreExports.cmake not found

I'm trying to use your ppa to install cgal here but it doesn't work because CGAL_CoreExports.cmake is not found.

see this section of diff -u xxx/logs/toothless.log xxx/logs/travis_patchA.log where toothless is the log of my laptop using ubuntu 17.10 and travis_patchA.log is a travis container using nextgis/ppa.

 /usr/lib/x86_64-linux-gnu/cmake/CGAL/CGALConfig.cmake(79):  if(EXISTS /usr/lib/x86_64-linux-gnu/cmake/CGAL/CGAL_CoreExports.cm
ake )
-/usr/lib/x86_64-linux-gnu/cmake/CGAL/CGALConfig.cmake(81):  include(/usr/lib/x86_64-linux-gnu/cmake/CGAL/CGAL_CoreExports.cmake )
-/usr/lib/x86_64-linux-gnu/cmake/CGAL/CGALConfig.cmake(83):  include(/usr/lib/x86_64-linux-gnu/cmake/CGAL/CGAL_CoreLibConfig.cmake )
 /usr/lib/x86_64-linux-gnu/cmake/CGAL/CGALConfig.cmake(86):  if(WITH_CGAL_Core )

Some more info regarding libcgal-dev:

In toothless:


❯ apt-cache policy libcgal-dev  
libcgal-dev:
Installed: 4.9-1build2
Candidate: 4.9-1build2
Version table:
*** 4.9-1build2 500
    500 http://archive.ubuntu.com/ubuntu artful/universe amd64 Packages
    100 /var/lib/dpkg/status


- In travis container: 
```sh
travis@8aa541f863ac:~/openmeeg/build$ apt-cache policy libcgal-dev
libcgal-dev:
  Installed: 4.9+17-0trusty1
  Candidate: 4.9+17-0trusty1
  Version table:
 *** 4.9+17-0trusty1 500
        500 http://ppa.launchpad.net/nextgis/ppa/ubuntu trusty/main amd64 Packages
        100 /var/lib/dpkg/status
     4.2-5ubuntu1 500
        500 http://archive.ubuntu.com/ubuntu trusty/universe amd64 Packages

nextgis / ppa

cgal /usr/lib/x86_64-linux-gnu/cmake/CGAL/CGAL_CoreExports.cmake not found #5