use a constraints file for virtualenv install

constraints.txt

@@ -1 +1,89 @@
+AccessControl==4.0b4
+Acquisition==4.4.4
+AuthEncoding==4.0.0
+BTrees==4.5.0
+Chameleon==3.4
+DateTime==4.2
+DocumentTemplate==3.0b3
+ExtensionClass==4.3.0
+Missing==4.0.1
+MultiMapping==4.0
+PasteDeploy==1.5.2
+Persistence==3.0b3
+Products.BTreeFolder2==4.0.0
+Products.ZCTextIndex==4.0.2
+Products.ZCatalog==4.1
+Record==3.4
+RestrictedPython==4.0b5
+WSGIProxy2==0.4.4
+WebOb==1.8.1
+WebTest==2.0.29
+ZConfig==3.2.0
+ZEO==5.2.0
+ZODB==5.4.0
 ZServer==4.0b1 ; python_version < '3.0'
+Zope2==4.0b1
+five.globalrequest==99.1
+five.localsitemanager==3.1
+funcsigs==1.0.2
+future==0.16.0
+ipaddress==1.0.22
+mock==2.0.0
+pbr==4.0.3
+persistent==4.2.4.2
+pytz==2018.4
+shutilwhich==1.1.0
+six==1.11.0
+transaction==2.2.1
+waitress==1.1.0
+z3c.pt==3.1.0
+zExceptions==4.0
+zc.lockfile==1.3.0
+zdaemon==4.2.0
+zodbpickle==1.0.1
+zope.annotation==4.6.0
+zope.browser==2.2.0
+zope.browsermenu==4.3.0
+zope.browserpage==4.2.0
+zope.browserresource==4.2.1
+zope.cachedescriptors==4.3.1
+zope.component==4.4.1
+zope.componentvocabulary==2.1.0
+zope.configuration==4.1.0
+zope.container==4.2.1
+zope.contentprovider==4.1.0
+zope.contenttype==4.3.0
+zope.datetime==4.2.0
+zope.deferredimport==4.2.1
+zope.deprecation==4.3.0
+zope.dottedname==4.2.0
+zope.event==4.3.0
+zope.exceptions==4.2.0
+zope.filerepresentation==4.2.0
+zope.formlib==4.4
+zope.globalrequest==1.4
+zope.i18n==4.3.1
+zope.i18nmessageid==4.1.0
+zope.interface==4.5.0
+zope.lifecycleevent==4.2.0
+zope.location==4.1.0
+zope.pagetemplate==4.3.0
+zope.processlifetime==2.2.0
+zope.proxy==4.3.0
+zope.ptresource==4.1.0
+zope.publisher==4.3.2
+zope.ramcache==2.2.0
+zope.schema==4.5.0
+zope.security==4.2.2
+zope.sendmail==4.1.0
+zope.sequencesort==4.0.1
+zope.site==4.1.0
+zope.size==4.2.0
+zope.structuredtext==4.2.0
+zope.tal==4.3.1
+zope.tales==4.2.0
+zope.testbrowser==5.2.4
+zope.testing==4.6.2
+zope.testrunner==4.8.1
+zope.traversing==4.2.0
+zope.viewlet==4.1.0

docs/INSTALL-virtualenv.rst

@@ -28,7 +28,7 @@ If you are still using Python 2.7 install `virtualenv` onto your system then cal
    New python executable in zope/bin/python2.7
    Installing setuptools, pip, wheel...done.
    $ cd zope
-   
+
 Make sure you use at least version ``12.0.1`` of `virtualenv`.
 (Calling ``virtualenv --version`` tells you the used version number.)
 Older versions install a `pip` version which is not compatible with the file format
@@ -44,13 +44,25 @@ version of ``requirements-full.txt`` in the URL, replacing 4.0b6 in the example
 
 .. code-block:: sh
 
-   $ bin/pip install \
-   -r https://zopefoundation.github.io/Zope/releases/4.0b6/requirements-full.txt
+   $ bin/pip install Zope==4.0b6\
+   -c https://zopefoundation.github.io/Zope/releases/4.0b6/constraints.txt
+   ...
    Obtaining Zope
    ...
    Successfully installed ...
 
-If you are on Python 2 and want to use ZServer instead of WSGI , you'll have to 
+
+Or you can install Zope using a single requirements file. Note that this
+installation method might install packages that are not actually needed (i.e.
+are not listed in the ``install_requires`` section of ``setup.py``
+
+ .. code-block:: sh
+
+-   $ bin/pip install \
+-   -r https://zopefoundation.github.io/Zope/releases/4.0b6/requirements-full.txt
+
+
+If you are on Python 2 and want to use ZServer instead of WSGI , you'll have to
 install that package seperately using the version spec in constraints.txt
 
 .. code-block:: sh

util.py

@@ -45,6 +45,7 @@ def generate(in_, requirements_file, constraints_file):
             constraints.append(spec + '\n')
         else:
             requirements.append(spec + '\n')
+            constraints.append(spec + '\n')
 
     with open(out_file_requirements, 'w') as fd:
         fd.write(zope_requirement)