Unable to set build variables conditionally using this task

[gandhiprachi]

Repro steps
I have a shell script like this
abort=true
if [ "$BUILD_SOURCEBRANCH" = "master" ] || [ $isCi = "1" ]; then
abort=false
fi
echo $abort
if [ "$abort" = true ]; then
echo "##vso[task.complete result=Canceled;]"
echo "##vso[task.setvariable variable=agent.jobstatus;]canceled"
fi

Actual Result
When abort = true, i see the correct behavior and the step and build are canceled.
When abort=false, i see that the step is marked as canceled even though build doesn't halt.

Expected Result
When abort=false, step shouldn't be canceled.

I see shell script source is printed before tempexecution.sh executes. I wonder if this printing of echo commands has something to do with this behavior.