macvim compiles with wrong python version (and not working with needed version)

[ilya belsky]

In brief:

I have a problem with compiling macvim with preferred python version.
When I use --enable-pythoninterp it compiles with system OSX python version.
When I use --enable-pythoninterp=dynamic I get an error in vim while trying :py import sys

Here is what I was doing in more detail:

% git clone https://github.com/b4winckler/macvim.git
% cd macvim
% ./configure --enable-pythoninterp \
     --with-python-config-dir=/usr/local/lib/python2.7/config <- this option has no affects on result
...
checking for python... /usr/local/bin/python
checking Python version... 2.7
checking Python is 1.4 or better... yep
checking Python's install prefix... /usr/local
checking Python's execution prefix... /usr/local
checking Python's configuration directory... /usr/local/lib/python2.7/config
...
% make
...
** BUILD SUCCEEDED **
% open src/MacVim/build/Release/MacVim.app

In the opened MacVim I type:

:py import sys; print (sys.version, sys.executable)
('2.6.1 (r261:67515, Jun 24 2010, 21:47:49)
  [GCC 4.2.1 (Apple Inc. build 5646)]',
 '/usr/bin/python')

Why 2.6.1?
Why /usr/bin/python?
My default python is 2.7! And it lives at /usr/local/bin/python
I was searching for solution all day. And I found it. It is =dynamic attribute (but this solution had not explanation).

After that I tried to recompile vim with dynamic python:

% ./configure --enable-pythoninterp=dynamic
... output the same ...
% make
% open src/MacVim/build/Release/MacVim.app

In opened MacVim:

:py import sys

And here comes an error:

E370: Could not load library libpython2.7.a
E263: Sorry, this command is disabled, the Python library could not be loaded.

---

My OSX version is 10.6.8.
Default python version is 2.7.

% which python
/usr/local/bin/python

Can anybody explain how python is integrating into vim during the compilation?
And how to fix the error with libpython2.7.a?