Explain why tasks are not up-to-date on snapshot archives upload

[szpak]

On the Travis script execution:

script: ./gradlew check funcTest install -s --continue && jdk_switcher use oraclejdk8 &&
        ./scripts/runTests.sh && jdk_switcher use $TRAVIS_JDK_VERSION &&
        ./gradlew uploadSnapshotArchives -s

in the last command (uploadSnapshotArchives) tasks are not treated as up-to-date which increase the execution time dramatically (e.g. test are executed again). Currently there is a workaround with -x check, but it would be good to explain the reason.