Forms aren’t immediately showing up in push or export after a canceled pull - only with Java 8

[mmarciniak90]

Software versions

Briefcase v1.17.4, Java v1.8

Problem description

Forms aren’t immediately showing up in push or export after a canceled pull

Steps to reproduce the problem

1. Start a pull operation and cancel it
2. Go to push or export tab
3. Forms aren’t immediately showing up in push or export after a pull

Expected behavior

Forms are immediately showing up in push or export after a pull

Notes

Discovered during testing #884