Revert "travis: filter out pyenv"

This reverts commit aa2e0f09ec.

.travis.yml

@@ -40,7 +40,6 @@ env:
 
 before_install:
     - export PATH=$(echo $PATH | tr ':' "\n" | sed '/\/opt\/python/d' | tr "\n" ":" | sed "s|::|:|g")
-    - export PATH=$(echo $PATH | tr ':' "\n" | sed '/\/opt\/pyenv/d' | tr "\n" ":" | sed "s|::|:|g")
 install:
     - if [ -n "$DPKG_ADD_ARCH" ]; then sudo dpkg --add-architecture "$DPKG_ADD_ARCH" ; fi
     - if [ -n "$PACKAGES" ]; then travis_retry sudo apt-get update; fi