How to reproduce:
1. Create a new Unity project
2. Press the Command+B hotkey
3. Press 'Cancel' in the window, that pops up

Expected result: the window does not pop up again
Actual result: the same window pops up again

Reproducible with: 2018.3.0a6, 2018.3.0b1
Not reproducible with: 2018.2.7f1, 2018.3.0a5

Notes:
Issue reproduction is not 100% consistent
The issue seems to occur much more often in 2018.3.0a6 than in 2018.3.0b1
If instead of pressing 'Cancel' in the pop-up window a name is set and the project is built, after it is finished, another one will immediately start building