Fix test_embed

Signed-off-by: Filipe Laíns <lains@riseup.net>

Author: FFY00

Modules/getpath.py

@@ -641,9 +641,12 @@ def search_up(prefix, *landmarks, test=isfile):
 
 # For a venv, update the main prefix/exec_prefix but leave the base ones unchanged
 if venv_prefix:
-    base_prefix = prefix
-    base_exec_prefix = exec_prefix
-    prefix = exec_prefix = venv_prefix
+    if not prefix:
+        base_prefix = prefix
+        prefix = venv_prefix
+    if not exec_prefix:
+        base_exec_prefix = exec_prefix
+        exec_prefix = venv_prefix
 
 
 # After calculating prefix and exec_prefix, use their values for base_prefix and
@@ -758,9 +761,12 @@ def search_up(prefix, *landmarks, test=isfile):
 # QUIRK: Non-Windows replaces prefix/exec_prefix with defaults when running
 # in build directory. This happens after pythonpath calculation.
 # Virtual environments using the build directory Python still keep their prefix.
-if not venv_prefix and os_name != 'nt' and build_prefix:
-    prefix = config.get('prefix') or PREFIX
-    exec_prefix = config.get('exec_prefix') or EXEC_PREFIX or prefix
+if os_name != 'nt' and build_prefix:
+    base_prefix = config.get('base_prefix') or PREFIX
+    base_exec_prefix = config.get('base_exec_prefix') or EXEC_PREFIX or prefix
+    if not venv_prefix:
+        prefix = config.get('prefix') or base_prefix
+        exec_prefix = config.get('exec_prefix') or base_exec_prefix
 
 
 # ******************************************************************************