src/lxml / etree defs.h: 9: 31: error fatal: libxml/xmlversion.h: No hay tal archivo o directorio

1. Estoy ejecutando el siguiente comando para instalar los paquetes en ese archivo " pip install -r requirements.txt --download-cache=~/tmp/pip-cache".

2. Requisito.txt contiene pacakages como

# Data formats
# ------------
PIL==1.1.7 # 

html5lib==0.90
httplib2==0.7.4
lxml==2.3.1

# Documentation
# -------------
Sphinx==1.1
docutils==0.8.1

# Testing
# -------
behave==1.1.0
dingus==0.3.2
django-testscenarios==0.7.2
mechanize==0.2.5
mock==0.7.2
testscenarios==0.2
testtools==0.9.14
wsgi_intercept==0.5.1

Mientras viene a instalar paquetes "lxml" estoy recibiendo el siguiente eror

Requirement already satisfied (use --upgrade to upgrade): django-testproject>=0.1.1 in /usr/lib/python2.7/site-packages/django_testproject-0.1.1-py2.7.egg (from django-testscenarios==0.7.2->-r requirements.txt (line 33))
Installing collected packages: lxml, Sphinx, docutils, behave, dingus, mock, testscenarios, testtools, South
  Running setup.py install for lxml
    Building lxml version 2.3.1.
    Building without Cython.
    ERROR: /bin/sh: xslt-config: command not found

    ** make sure the development packages of libxml2 and libxslt are installed **

    Using build configuration of libxslt
    building 'lxml.etree' extension
    gcc -pthread -fno-strict-aliasing -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m32 -march=i686 -mtune=atom -fasynchronous-unwind-tables -D_GNU_SOURCE -fPIC -fwrapv -DNDEBUG -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m32 -march=i686 -mtune=atom -fasynchronous-unwind-tables -D_GNU_SOURCE -fPIC -fwrapv -fPIC -I/usr/include/python2.7 -c src/lxml/lxml.etree.c -o build/temp.linux-i686-2.7/src/lxml/lxml.etree.o -w
    In file included from src/lxml/lxml.etree.c:239:0:
    src/lxml/etree_defs.h:9:31: fatal error: libxml/xmlversion.h: No such file or directory
    compilation terminated.
    error: command 'gcc' failed with exit status 1
    Complete output from command /usr/bin/python -c "import setuptools;__file__='/root/Projects/ir/build/lxml/setup.py';execfile(__file__)" install --single-version-externally-managed --record /tmp/pip-SwjFm3-record/install-record.txt:
    Building lxml version 2.3.1.

Building without Cython.

ERROR: /bin/sh: xslt-config: command not found



** make sure the development packages of libxml2 and libxslt are installed **



Using build configuration of libxslt

running install

running build

running build_py

copying src/lxml/cssselect.py -> build/lib.linux-i686-2.7/lxml

copying src/lxml/__init__.py -> build/lib.linux-i686-2.7/lxml

copying src/lxml/sax.py -> build/lib.linux-i686-2.7/lxml

copying src/lxml/pyclasslookup.py -> build/lib.linux-i686-2.7/lxml

copying src/lxml/usedoctest.py -> build/lib.linux-i686-2.7/lxml

copying src/lxml/doctestcompare.py -> build/lib.linux-i686-2.7/lxml

copying src/lxml/_elementpath.py -> build/lib.linux-i686-2.7/lxml

copying src/lxml/ElementInclude.py -> build/lib.linux-i686-2.7/lxml

copying src/lxml/builder.py -> build/lib.linux-i686-2.7/lxml

copying src/lxml/html/clean.py -> build/lib.linux-i686-2.7/lxml/html

copying src/lxml/html/__init__.py -> build/lib.linux-i686-2.7/lxml/html

copying src/lxml/html/_dictmixin.py -> build/lib.linux-i686-2.7/lxml/html

copying src/lxml/html/ElementSoup.py -> build/lib.linux-i686-2.7/lxml/html

copying src/lxml/html/usedoctest.py -> build/lib.linux-i686-2.7/lxml/html

copying src/lxml/html/defs.py -> build/lib.linux-i686-2.7/lxml/html

copying src/lxml/html/builder.py -> build/lib.linux-i686-2.7/lxml/html

copying src/lxml/html/_html5builder.py -> build/lib.linux-i686-2.7/lxml/html

copying src/lxml/html/diff.py -> build/lib.linux-i686-2.7/lxml/html

copying src/lxml/html/html5parser.py -> build/lib.linux-i686-2.7/lxml/html

copying src/lxml/html/_diffcommand.py -> build/lib.linux-i686-2.7/lxml/html

copying src/lxml/html/_setmixin.py -> build/lib.linux-i686-2.7/lxml/html

copying src/lxml/html/soupparser.py -> build/lib.linux-i686-2.7/lxml/html

copying src/lxml/html/formfill.py -> build/lib.linux-i686-2.7/lxml/html

copying src/lxml/isoschematron/__init__.py -> build/lib.linux-i686-2.7/lxml/isoschematron

copying src/lxml/etreepublic.pxd -> build/lib.linux-i686-2.7/lxml

copying src/lxml/tree.pxd -> build/lib.linux-i686-2.7/lxml

copying src/lxml/etree_defs.h -> build/lib.linux-i686-2.7/lxml

copying src/lxml/isoschematron/resources/rng/iso-schematron.rng -> build/lib.linux-i686-2.7/lxml/isoschematron/resources/rng

copying src/lxml/isoschematron/resources/xsl/XSD2Schtrn.xsl -> build/lib.linux-i686-2.7/lxml/isoschematron/resources/xsl

copying src/lxml/isoschematron/resources/xsl/RNG2Schtrn.xsl -> build/lib.linux-i686-2.7/lxml/isoschematron/resources/xsl

copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_svrl_for_xslt1.xsl -> build/lib.linux-i686-2.7/lxml/isoschematron/resources/xsl/iso-schematron-xslt1

copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_schematron_message.xsl -> build/lib.linux-i686-2.7/lxml/isoschematron/resources/xsl/iso-schematron-xslt1

copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_schematron_skeleton_for_xslt1.xsl -> build/lib.linux-i686-2.7/lxml/isoschematron/resources/xsl/iso-schematron-xslt1

copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_abstract_expand.xsl -> build/lib.linux-i686-2.7/lxml/isoschematron/resources/xsl/iso-schematron-xslt1

copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/iso_dsdl_include.xsl -> build/lib.linux-i686-2.7/lxml/isoschematron/resources/xsl/iso-schematron-xslt1

copying src/lxml/isoschematron/resources/xsl/iso-schematron-xslt1/readme.txt -> build/lib.linux-i686-2.7/lxml/isoschematron/resources/xsl/iso-schematron-xslt1

running build_ext

building 'lxml.etree' extension

gcc -pthread -fno-strict-aliasing -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m32 -march=i686 -mtune=atom -fasynchronous-unwind-tables -D_GNU_SOURCE -fPIC -fwrapv -DNDEBUG -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m32 -march=i686 -mtune=atom -fasynchronous-unwind-tables -D_GNU_SOURCE -fPIC -fwrapv -fPIC -I/usr/include/python2.7 -c src/lxml/lxml.etree.c -o build/temp.linux-i686-2.7/src/lxml/lxml.etree.o -w

In file included from src/lxml/lxml.etree.c:239:0:

src/lxml/etree_defs.h:9:31: fatal error: libxml/xmlversion.h: No such file or directory

compilation terminated.

error: command 'gcc' failed with exit status 1

----------------------------------------
Command /usr/bin/python -c "import setuptools;__file__='/root/Projects/ir/build/lxml/setup.py';execfile(__file__)" install --single-version-externally-managed --record /tmp/pip-SwjFm3-record/install-record.txt failed with error code 1
Storing complete log in /root/.pip/pip.log

¿Puede alguien comprobar y guiarme cuál sería el problema y por qué?Cualquier paquete que falte para instalar.