:noweb expansion happens before :prologue expansion. Why?

:noweb expansion happens before :prologue expansion. Why?

[Vladimir Nikishkin]

Hello, everyone

I wanted to do the following
#+name: common
#+begin_src scheme
(display "Common header\n")
#+end_src

#+begin_src scheme :noweb yes :prologue "<<common>>"
(display "particular block")
#+end_src

This fails, because :prologue is language-specific, and is expanded
later than :noweb, so I am getting <<common>> in my code rather than
the expansion.

Why? Only four language modules care to implement :prologue (R,
scheme, maxima, gnuplot) , and all of them do it by just concatenating
it with the rest of the code, and as a result the wonderful
possibility of attaching common headers to blocks is greatly reduced,
since they are not expanded at all.

Would it make more sense to expand the :prologue and :epilogue
_before_ :noweb rather than after and do it in a uniform way (that is,
simply concatenate)?

I am ready to make a patch, as long as it won't be rejected.

-- 
Yours sincerely, Vladimir Nikishkin