SBT_ETC_FILE

Travis CI adds `/etc/sbt/sbtopts` that prevents us from testing the out-of-box behavior. This allows us to override the location.

.travis.yml

@@ -11,6 +11,8 @@ env:
     - TRAVIS_JDK=adopt@1.8.212-04
     - JABBA_HOME=$HOME/.jabba
     - TRAVIS_JDK11=openjdk@1.11.0
+    ## ignore Travis CI's default /etc/sbt/sbtopts
+    - SBT_ETC_FILE=$HOME/etc/sbt/sbtopts
 
 matrix:
   include:
@@ -41,6 +43,7 @@ matrix:
       install:
         - $JABBA_HOME/bin/jabba install $TRAVIS_JDK && export JAVA_HOME="$JABBA_HOME/jdk/$TRAVIS_JDK/Contents/Home" && export PATH="$JAVA_HOME/bin:$PATH"
         - java -Xmx32m -version
+        - unset SBT_OPTS
       script:
         - sbt -Dsbt.build.version=$SBT_VER universal:packageBin
         - cd citest && ./test.sh
@@ -72,6 +75,7 @@ before_install:
 install:
   - $JABBA_HOME/bin/jabba install $TRAVIS_JDK && export JAVA_HOME="$JABBA_HOME/jdk/$TRAVIS_JDK" && export PATH="$JAVA_HOME/bin:$PATH"
   - java -Xmx32m -version
+  - unset SBT_OPTS
 
 cache:
   directories:

src/universal/bin/sbt

@@ -385,6 +385,8 @@ run() {
 declare -r noshare_opts="-Dsbt.global.base=project/.sbtboot -Dsbt.boot.directory=project/.boot -Dsbt.ivy.home=project/.ivy"
 declare -r sbt_opts_file=".sbtopts"
 declare -r etc_sbt_opts_file="/etc/sbt/sbtopts"
+# this allows /etc/sbt/sbtopts location to be changed
+declare -r etc_file="${SBT_ETC_FILE:-$etc_sbt_opts_file}"
 declare -r dist_sbt_opts_file="${sbt_home}/conf/sbtopts"
 declare -r win_sbt_opts_file="${sbt_home}/conf/sbtconfig.txt"
 
@@ -546,7 +548,7 @@ loadConfigFile() {
 [[ -f "$dist_sbt_opts_file" ]] && set -- $(loadConfigFile "$dist_sbt_opts_file") "$@"
 
 # Here we pull in the global settings configuration.
-[[ -f "$etc_sbt_opts_file" ]] && set -- $(loadConfigFile "$etc_sbt_opts_file") "$@"
+[[ -f "$etc_file" ]] && set -- $(loadConfigFile "$etc_file") "$@"
 
 # Pull in the project-level config file, if it exists.
 [[ -f "$sbt_opts_file" ]] && set -- $(loadConfigFile "$sbt_opts_file") "$@"