--- /dev/null
+diff --git a/Lib/site.py b/Lib/site.py
+--- a/Lib/site.py
++++ b/Lib/site.py
+@@ -262,7 +266,7 @@ def addusersitepackages(known_paths):
+ # this call will also make sure USER_BASE and USER_SITE are set
+ user_site = getusersitepackages()
+
+- if ENABLE_USER_SITE and os.path.isdir(user_site):
++ if ENABLE_USER_SITE and user_site and os.path.isdir(user_site):
+ addsitedir(user_site, known_paths)
+ return known_paths
+
+diff --git a/Lib/sysconfig.py b/Lib/sysconfig.py
+--- a/Lib/sysconfig.py
++++ b/Lib/sysconfig.py
+@@ -170,7 +170,13 @@ def _expand_vars(scheme, vars):
+ for key, value in _INSTALL_SCHEMES[scheme].items():
+ if os.name in ('posix', 'nt'):
+ value = os.path.expanduser(value)
+- res[key] = os.path.normpath(_subst_vars(value, vars))
++ try:
++ path = _subst_vars(value, vars)
++ except AttributeError:
++ # a substitution variable doesn't exist (eg. '{userbase}'),
++ # don't create the variable
++ continue
++ res[key] = os.path.normpath(path)
+ return res
+
+ def _get_default_scheme():
+@@ -488,7 +494,12 @@ def get_config_vars(*args):
+ # Setting 'userbase' is done below the call to the
+ # init function to enable using 'get_config_var' in
+ # the init-function.
+- _CONFIG_VARS['userbase'] = _getuserbase()
++ try:
++ _CONFIG_VARS['userbase'] = _getuserbase()
++ except KeyError:
++ # catch getpwuid() error: don't create the variable if the user
++ # doesn't exist
++ pass
+
+ if 'srcdir' not in _CONFIG_VARS:
+ _CONFIG_VARS['srcdir'] = _PROJECT_BASE