In version 1.1.5 of bitbucket plugin a following change was added:

• fix JENKINS-32372 Inject the Payload into the build through $BITBUCKET_PAYLOAD

The issue with this change is when payload is too big - builds using nunit test runner fail with a following message:

System.InvalidOperationException: The environment block used to start a process cannot be longer than 65535 bytes.  Your environment block is 68162 bytes long.  Remove some environment variables and try again. 

After we looked into what environment block contains we found out that BITBUCKET_PAYLOAD is the reason for this failure. This can be easily workaround by restarting build manually or with one more simple change but in some complicated scenarios this is not an option