For the record, this made unloaded interpreter startup quite a bit slower since importing one of the abcs now imports the whole collection package and its dependencies.
From 3.2 to 3.3:

### normal_startup ###
Min: 0.842961 -> 1.091329: 1.29x slower
Avg: 0.851607 -> 1.106344: 1.30x slower
Significant (t=-37.61)
Stddev: 0.00623 -> 0.01381: 2.2162x larger
Timeline: http://tinyurl.com/3etyx44

### startup_nosite ###
Min: 0.247490 -> 0.378279: 1.53x slower
Avg: 0.255694 -> 0.382722: 1.50x slower
Significant (t=-39.46)
Stddev: 0.00865 -> 0.00536: 1.6141x smaller
Timeline: http://tinyurl.com/3vovjwb

It probably doesn't make much difference in practice, since collections is one of those modules everyone will use in their code.