CI/DOC: fix clipboard on travis (#26103)

Co-authored-by: Joris Van den Bossche <jorisvandenbossche@gmail.com>

Author: saurav-chakravorty

.travis.yml

@@ -86,6 +86,14 @@ install:
   - ci/submit_cython_cache.sh
   - echo "install done"
 
+before_script:
+  # display server (for clipboard functionality) needs to be started here,
+  # does not work if done in install:setup_env.sh (GH-26103)
+  - export DISPLAY=":99.0"
+  - echo "sh -e /etc/init.d/xvfb start"
+  - sh -e /etc/init.d/xvfb start
+  - sleep 3
+
 script:
   - echo "script start"
   - source activate pandas-dev

ci/setup_env.sh

@@ -118,16 +118,10 @@ echo "conda list"
 conda list
 
 # Install DB for Linux
-export DISPLAY=":99."
 if [ ${TRAVIS_OS_NAME} == "linux" ]; then
   echo "installing dbs"
   mysql -e 'create database pandas_nosetest;'
   psql -c 'create database pandas_nosetest;' -U postgres
-
-  echo
-  echo "sh -e /etc/init.d/xvfb start"
-  sh -e /etc/init.d/xvfb start
-  sleep 3
 else
    echo "not using dbs on non-linux"
 fi