If you are going to try to make patches, it is CRITICAL that you force a setting in your Eclipse preferences:
Window->Preferences->CVS :: Files and Folders Tab
Ensure that "Convert text files to use platform line encoding" is UN-checked.
If you have already checked out the jdbm project, check it out to a new eclipse project after you make the above setting change.
I have just wasted at least an hour and a half trying to figure out why my patches were coming out as total file patches (i.e. "Delete the whole thing, then replace with these contents").
This problem doesn't effect the Compare system in Eclipse, which makes it a total pain in the neck to figure out what is going on.
To make this even more interesting, it appears that some of the files in jdbm were stored with win32 CR/LF encoding, and others with unix encoding.
I'm still fighting with this darned thing - I've got changes I need to submit as patches, but I can't get the patch to create properly - a huge waste of time...