Description of problem:
When syncing with compression (-z), certain file types should not be compress during the transfer because they are already compressed. The file types which are not to be compressed can be seen in the man page.

Version-Release number of selected component (if applicable):
All versions since 3.1.0

How reproducible:
Always

Steps to Reproduce:
1. run 'rm -f Z ; rsync -azv alpha:z.gz Z'

Actual results:
Transferred data was compressed during the transfer:
sent 43 bytes  received 63,873 bytes  25,566.40 bytes/sec
total size is 628,952  speedup is 9.84

Expected results:
No compression should happen.

Additional info:
Note that the source file 'z.gz' was an ascii text file to show clearly that compression took place.