AppVeyor tests seem failing with Arrow 0.15 - https://github.com/apache/spark/pull/26041
We should set ARROW_PRE_0_15_IPC_FORMAT to 1.
Bump up the minimum Arrow version as 0.15.1 in SparkR
Uses Arrow R 0.14.1 in AppVeyor for now
Upgrade Apache Arrow to 0.15.1
pandas udf not working with latest pyarrow release (0.15.0)
GitHub Pull Request #26555
GitHub Pull Request #26566