title: Using Conan with Python3 on Travis-CI
body: <p>I have a C++ project that uses Travis-CI and Conan. My Linux build on Travis-CI is failing when it attempts to download libcurl:</p>
  
  <pre><code>libcurl/7.61.1@bincrafters/stable: Building your package in /home/travis/.conan/data/libcurl/7.61.1/bincrafters/stable/build/b6dbf799dd7e6d1c740e159bea361666320a3db8
  libcurl/7.61.1@bincrafters/stable: Configuring sources in /home/travis/.conan/data/libcurl/7.61.1/bincrafters/stable/source
  /usr/local/lib/python2.7/dist-packages/urllib3/util/ssl_.py:150: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
    InsecurePlatformWarning
  ERROR: Error downloading file https://curl.haxx.se/download/curl-7.61.1.tar.gz: 'HTTPSConnectionPool(host='curl.haxx.se', port=443): Max retries exceeded with url: /download/curl-7.61.1.tar.gz (Caused by SSLError(CertificateError("hostname 'curl.haxx.se' doesn't match 'c.sni.fastly.net'",),))'
  Waiting 5 seconds to retry...
  /usr/local/lib/python2.7/dist-packages/urllib3/util/ssl_.py:150: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/advanced-usage.html#ssl-warnings
    InsecurePlatformWarning
  libcurl/7.61.1@bincrafters/stable: WARN: Trying to remove corrupted source folder
  libcurl/7.61.1@bincrafters/stable: WARN: This can take a while for big packages
  ERROR: libcurl/7.61.1@bincrafters/stable: Error in source() method, line 131
      tools.get("https://curl.haxx.se/download/curl-%s.tar.gz" % self.version)
      ConanException: Error downloading file https://curl.haxx.se/download/curl-7.61.1.tar.gz: 'HTTPSConnectionPool(host='curl.haxx.se', port=443): Max retries exceeded with url: /download/curl-7.61.1.tar.gz (Caused by SSLError(CertificateError("hostname 'curl.haxx.se' doesn't match 'c.sni.fastly.net'",),))'
  The command "conan install .. --build missing" exited with 1.
  </code></pre>
  
  <p>Per the advise in the error, I have tried to get Travis to use Python3 to see if that would resolve the problem but I have had no luck. First I added <code>python3</code> to my <code>packages:</code> like so:</p>
  
  <pre><code>matrix:
    include:
      - os: linux
        dist: trusty
        sudo: required
        env:
          - CC_COMPILER=gcc-7
          - CXX_COMPILER=g++-7
          - BUILD_TYPE=RelWithDebInfo
        addons:
          apt:
            packages:
              - python3
              - gcc-7
              - g++-7
            sources:
              - ubuntu-toolchain-r-test
  </code></pre>
  
  <p>But I received the same error as above. Then I tried <code>alias</code>'ing the command:</p>
  
  <pre><code>install:
    - |
      if [[ "${TRAVIS_OS_NAME}" == "linux" ]]; then
        sudo pip install conan
        alias python=python3
      fi
  </code></pre>
  
  <p>Yet, I get the same results. </p>
  
  <p>How can I get Travis-CI to use python3 for Conan? Or is there another way I can get my <code>conan install</code> command to work?</p>
  
  <p>Thank you!</p>