Exclude dulwich 0.19.3 from global requirements

dulwich 0.19.3 is broken due to [1],
we need to exclude this specific version
to avoid problems.

If we use this version will produce this kind of errors:

UnicodeDecodeError: 'ascii' codec can't decode
byte 0xc4 in position 48: ordinal not in range(128)

Because there are unicode characters in the setup.cfg
for this version.

[1]:  jelmer/dulwich@1b6509f

Depends-On: Icabb56b9c6b2d99d78a7e1a77f8fe7a4ea6fa0c8
Change-Id: I1f80bc81917f768e1ecb55aebdd5fc84e056b229

global-requirements.txt

@@ -49,7 +49,7 @@ dnspython3!=1.13.0,!=1.14.0;python_version>='3.0'  # http://www.dnspython.org/LI
 docutils  # OSI-Approved Open Source, Public Domain
 dogpile.cache  # BSD
 dogtag-pki  # LGPLv3+
-dulwich  # Apache-2.0
+dulwich!=0.19.3  # Apache-2.0
 elasticsearch<=3.0.0  # Apache-2.0
 enum34;python_version=='2.7' or python_version=='2.6' or python_version=='3.3'  # BSD
 # NOTE: New versions of eventlet should not be accepted lightly