Changes to copyfile functionality.

It seems to me that there are at least three improvements which should be made to copyfile: 1. If the file on the overlord and minion are the same, that file should not be copied. This saves bandwidth/processing time. 2. Overwriting the file on the minion should be atomic, e.g. the file on the overlord should be copied to a tempfile on the minion then moved to overwrite the target file as a final step. Right now if funcd dies or something goes wrong mid-copy you end up with half a file on the minion. 3. There should be an option (off by default) such that if the file which has been copied over to the minion is not identical to the file on the overlord it is re-copied, or at least does not overwrite the file on the minion. This won't work for some files (busy logfiles) but for most files it seems like an extra bit of reliability which most people would want in most situations. I submitted a patch (though not a git-patch... my bad!) back in January 2011 which implements #1, but imperfectly. The overlord still has to send a (small) packet to the minion for each 60KB chunk of target file. Would anyone be bothered terribly if I worked on #2 and #3? While I am at it I will try to find a way to fix up my patch for #1 as well. There is some overlap between these patches. Both will involve calculating an MD5 hash of the file on the overlord, for example. P.S. Is the new mailing list on fedorahosted.org live yet? I am sending this message to both just in case. -- Marcus