cbrestore, cbtransfer exit with ImportError: No module named zlib if python installation on the box does not have zlib library ( when python is built from source )

build 1965

./cbrestore
Traceback (most recent call last):
  File "/opt/couchbase/lib/python/cbrestore", line 8, in <module>
    import pump_transfer
  File "/opt/couchbase/lib/python/pump_transfer.py", line 10, in <module>
    import pump
  File "/opt/couchbase/lib/python/pump.py", line 14, in <module>
    import zlib
ImportError: No module named zlib

by default zlib module is disabled in python, it can be enabled using option --with-zlib when configure python.

but user at least should be notified about this requirements for cbrestore