OSI-approved license that assigns contributor copyright to me

[David Barrett]

I've developed an application from scratch, and thus I own the copyright 
  on the entire codebase.  I'd like to dual-license the codebase, once 
under an OSI-approved open-souce license, and a second time under a 
commercial license.  Naturally the question is how to incorporate code 
contributed under the OSI license into my commercial release.

For maximum flexibility, I would like to have the OSI license require 
contributors to transfer ownership of the copyright of their contributed 
code to me, thus enabling me to re-license it just as my own.  In this 
way, I retain total ownership over the copyright of the entire codebase, 
whether written by me or not.

Is there an OSI license that does this, or nearly this?

Reading through the list, it appears the QPL (Qt Public License) is the 
nearest.  However, (so far as I can tell -- it's rather complex) it 
doesn't explicitly transfer ownership over the copyright back to the 
"initial developer".  Indeed, the key paragraph is:

----
b. When modifications to the Software are released under this license, a 
non-exclusive royalty-free right is granted to the initial developer of 
the Software to distribute your modification in future versions of the 
Software provided such versions remain available under these terms in 
addition to any other license(s) of the initial developer.
----

Overall I find the entire license a bit confusing (who is the 'initial 
developer'?  Linus?  Charles Babbage?) and more complicated than I would 
think is necesasry.  Rather, I think the essential clauses would include 
something like:

1) You can modify the software so long as you give up all rights to the 
modification and immediately assign ownership of the modification's 
copyright to David Barrett

2) You can redistribute the compiled software so long as you make 
available for download the uncompiled source code

3) You can redistribute the modified or unmodified software in 
uncompiled souce code form so long as it is complete, non-obfuscated, 
blah blah legalese


Is there an OSI license that accomplishes this in a more straightforward 
and deliberate fashion than the QPL?  Thanks!

-david