Build error with current source release

Hi

I hope it is okay to ask such a question here.

I cloned the current source tree and tried to build it and I get the following error. Could someone tell me why and if there is an easy way to fix it? I’m running on a Mac and everything ran fine up to this error. Is is an excerpt from my typescript file.

Script started on Mon Feb 23 13:43:01 2015
    XMLTO git-add.1
xmlto: /Users/jr/Documents/projects/git/Documentation/git-add.xml does not validate (status 3)
xmlto: Fix document syntax or use --skip-validation option
I/O error : Attempt to load network entity http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd
/Users/jr/Documents/projects/git/Documentation/git-add.xml:2: warning: failed to load external entity "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"
D DocBook XML V4.5//EN" "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"
                                                                               ^
I/O error : Attempt to load network entity http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd
warning: failed to load external entity "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"
validity error : Could not load the external subset "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd"
Document /Users/jr/Documents/projects/git/Documentation/git-add.xml does not validate
make[1]: *** [git-add.1] Error 13
Script done on Mon Feb 23 13:43:33 2015

Thanks in advance for suggestions or solutions.

Best, J. R. Westmoreland