printf format code for integers is %d not %s.

Will backport.
diff --git a/PC/bdist_wininst/install.c b/PC/bdist_wininst/install.c
index bd83294..be4be37 100644
--- a/PC/bdist_wininst/install.c
+++ b/PC/bdist_wininst/install.c
@@ -617,7 +617,7 @@
 	if (h)
 		return h;
 	wsprintf(subkey_name,
-		 "SOFTWARE\\Python\\PythonCore\\%s.%s\\InstallPath",
+		 "SOFTWARE\\Python\\PythonCore\\%d.%d\\InstallPath",
 		 py_major, py_minor);
 	if (ERROR_SUCCESS != RegQueryValue(HKEY_CURRENT_USER, subkey_name,
 					   fullpath, &size))