libretro-buildbot-recipe.sh: Don't remove branches if travis is running the script.

travis/build-long.sh

@@ -4,6 +4,7 @@ export LOGDATE=`date +%Y-%m-%d`
 mkdir -p /tmp/log/${LOGDATE}
 export BOT=.
 export TMPDIR=/tmp
+export TRAVIS=1
 export EXIT_ON_ERROR=1
 
 # taken from https://stackoverflow.com/questions/26082444/how-to-work-around-travis-cis-4mb-output-limit

travis/build.sh

@@ -4,6 +4,7 @@ export LOGDATE=`date +%Y-%m-%d`
 mkdir -p /tmp/log/${LOGDATE}
 export BOT=.
 export TMPDIR=/tmp
+export TRAVIS=1
 export EXIT_ON_ERROR=1
 
 ./build-${PLATFORM}.sh