chore: avoid non-blocking IO for stdout to workaround "stdout: write …

…error" in Travis

Try workaround travis-ci/travis-ci#4704 (comment)

.travis/travis_build.sh

@@ -3,6 +3,9 @@ set -x -e
 
 if [[ "${FEDORA_CI}" == *"Y" ]];
 then
+  # Try to prevent "stdout: write error"
+  # WA is taken from https://github.com/travis-ci/travis-ci/issues/4704#issuecomment-348435959
+  python -c 'import os,sys,fcntl; flags = fcntl.fcntl(sys.stdout, fcntl.F_GETFL); fcntl.fcntl(sys.stdout, fcntl.F_SETFL, flags&~os.O_NONBLOCK);'
   export PARENT_VERSION=$(mvn -B -N org.apache.maven.plugins:maven-help-plugin:2.1.1:evaluate -Dexpression=project.parent.version | grep -v '\[')
   exec ./packaging/rpm_ci
 fi