Use latest sbt version in a travis build

Moving forward, it would be great for sbt to use the latest code to run
the scripted tests. This could help detect regressions that aren't
noticed by manual dogfooding. We can do this by first publishing
1.4.0-SNAPSHOT binaries before running tests. I didn't want to do this
for all of the builds because it does make each build that publishes
binaries take about a minute longer. The last build in the matrix is
much faster than the other builds though so I made just that build use
the snapshot version. Since that build almost always finishes first,
this should have little effect on the actual time to run ci even though
the cpu time will increase a bit.

.travis.yml

@@ -9,6 +9,8 @@ env:
     - SCALA_213=2.13.1
     - UTIL_TESTS="utilCache/test;utilControl/test;utilInterface/test;utilLogging/test;utilPosition/test;utilRelation/test;utilScripted/test;utilTracking/test"
     # WHITESOURCE_PASSWORD=
+    - SBT_VERSION_PROP=""
+    - SBT_LOCAL=false
     - secure: d3bu2KNwsVHwfhbGgO+gmRfDKBJhfICdCJFGWKf2w3Gv86AJZX9nuTYRxz0KtdvEHO5Xw8WTBZLPb2thSJqhw9OCm4J8TBAVqCP0ruUj4+aqBUFy4bVexQ6WKE6nWHs4JPzPk8c6uC1LG3hMuzlC8RGETXtL/n81Ef1u7NjyXjs=
   matrix:
     - SBT_CMD="mimaReportBinaryIssues ; javafmtCheck ; Test / javafmtCheck; scalafmtCheckAll ; scalafmtSbtCheck; serverTestProj/scalafmtCheckAll; headerCheck ;test:headerCheck ;whitesourceOnPush ;test:compile; publishLocal; test; serverTestProj/test; doc; $UTIL_TESTS; ++$SCALA_213; $UTIL_TESTS"
@@ -20,11 +22,14 @@ matrix:
   fast_finish: true
   include:
     - env:
+        - SBT_LOCAL=true
+        - SBT_VERSION_PROP=-Dsbt.version=1.4.0-SNAPSHOT
         - TRAVIS_JDK=adopt@1.8.0-222
         - SBT_CMD="++$SCALA_213; $UTIL_TESTS; ++$SCALA_212; $UTIL_TESTS; scripted actions/* source-dependencies/*1of3 dependency-management/*1of4 java/*"
 
 before_install:
   - curl -sL https://raw.githubusercontent.com/shyiko/jabba/0.11.0/install.sh | bash && . ~/.jabba/jabba.sh
+  - if [ $SBT_LOCAL == true ]; then sbt -Dsbt.io.virtual=false publishLocalBin; fi
 
 install:
   - $JABBA_HOME/bin/jabba install $TRAVIS_JDK
@@ -34,7 +39,7 @@ install:
 
 script:
   # It doesn't need that much memory because compile and run are forked
-  - sbt -Dsbt.io.virtual=false -Dsbt.ci=true -J-XX:ReservedCodeCacheSize=128m -J-Xmx800M -J-Xms800M -J-server "$SBT_CMD"
+  - sbt -Dsbt.io.virtual=false $SBT_VERSION_PROP -Dsbt.ci=true -J-XX:ReservedCodeCacheSize=128m -J-Xmx800M -J-Xms800M -J-server "$SBT_CMD"
 
 before_cache:
   - find $HOME/.cache/coursier/v1 -name "ivydata-*.properties" -delete