Add setup-eggs option in zc.recipe.egg:custom.

src/zc/buildout/easy_install.py

@@ -339,10 +339,13 @@ class Installer:
 
         tmp = tempfile.mkdtemp(dir=dest)
         try:
-            path = setuptools_loc
+            path_list = [setuptools_loc]
+            extra_path = os.environ.get('PYTHONEXTRAPATH')
+            if extra_path:
+                path_list += extra_path.split(os.pathsep)
 
             args = [sys.executable, '-c',
-                    ('import sys; sys.path[0:0] = [%r]; ' % path) +
+                    ('import sys; sys.path[0:0] = %r; ' % path_list) +
                     _easy_install_cmd, '-mZUNxd', tmp]
             level = logger.getEffectiveLevel()
             if level > 0:
@@ -353,8 +356,8 @@ class Installer:
             args.append(spec)
 
             if level <= logging.DEBUG:
-                logger.debug('Running easy_install:\n"%s"\npath=%s\n',
-                             '" "'.join(args), path)
+                logger.debug('Running easy_install:\n"%s"\npath_list=%r\n',
+                             '" "'.join(args), path_list)
 
             sys.stdout.flush() # We want any pending output first
 

zc.recipe.egg_/src/zc/recipe/egg/custom.py

@@ -83,6 +83,23 @@ class Custom(Base):
 
         distribution = options.get('egg', options.get('eggs', self.name)
                                    ).strip()
+
+        setup_eggs = [
+            r.strip()
+            for r in options.get('setup-eggs', '').split('\n')
+            if r.strip()]
+        if setup_eggs:
+            ws = zc.buildout.easy_install.install(
+                setup_eggs, options['_e'],
+                links=self.links,
+                index=self.index,
+                executable=sys.executable,
+                path=[options['_d'], options['_e']],
+                newest=self.newest,
+                )
+            extra_path = os.pathsep.join(ws.entries)
+            self.environment['PYTHONEXTRAPATH'] = os.environ['PYTHONEXTRAPATH'] = extra_path
+
         self._set_environment()
         try:
             return zc.buildout.easy_install.build(

zc.recipe.egg_/src/zc/recipe/egg/custom.rst

@@ -20,6 +20,10 @@ rpath
    A new-line separated list of directories to search for dynamic libraries
    at run time.
 
+setup-eggs
+   A new-line separated list of eggs that need to be installed
+   beforehand. It is useful to meet the `setup_requires` requirement.
+
 define
    A comma-separated list of names of C preprocessor variables to
    define.