Building from git repo on Win32

I have made successful builds of 8.5alpha3 on Win32 (XP, MSVC 8), but
I am getting missing files when attempting to build from current
fetches of the Git repository. I am new building PostgreSQL from
source, and am wondering if it is premature to attempt builds from the
repo?

Specifically, I am getting "No such file or directory" errors in
interfaces\ecpg for preproc.c and preproc.h

Project : error PRJ0002: Error result 1 returned from
'C:\WINDOWS\system32\cmd.exe'.
c1 : fatal error C1083: Cannot open source file:
'.\src\interfaces\ecpg\preproc\preproc.c': No such file or directory
.\src\interfaces\ecpg\preproc\parser.c(25): fatal error C1083: Cannot
open include file: 'preproc.h': No such file or directory
.\src\interfaces\ecpg\preproc\keywords.c(20): fatal error C1083:
Cannot open include file: 'preproc.h': No such file or
directory
.\src\interfaces\ecpg\preproc\ecpg_keywords.c(17): fatal error C1083:
Cannot open include file: 'preproc.h': No such file or directory
.\src\interfaces\ecpg\preproc\c_keywords.c(15): fatal error C1083:
Cannot open include file: 'preproc.h': No such file or directory
    0 Warning(s)
    6 Error(s)