Auto merge of #2120 - micbou:travis-pyenv, r=vheon

[READY] Fix pyenv setup on Travis

See PR Valloric/ycmd#460.

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ci/travis/travis_install.sh

@@ -17,10 +17,11 @@ source ci/travis/travis_install.${TRAVIS_OS_NAME}.sh
 
 export PYENV_ROOT="${HOME}/.pyenv"
 
-if [ ! -d "${PYENV_ROOT}" ]; then
+if [ ! -d "${PYENV_ROOT}/.git" ]; then
   git clone https://github.com/yyuu/pyenv.git ${PYENV_ROOT}
 fi
 pushd ${PYENV_ROOT}
+git fetch --tags
 git checkout v20160202
 popd