Issue #6074: Restore the long-broken support for running with read-only source files on Windows
diff --git a/Python/import.c b/Python/import.c
index 53c9b29..7daba06 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -910,6 +910,12 @@
     time_t mtime = srcstat->st_mtime;
 #ifdef MS_WINDOWS   /* since Windows uses different permissions  */
     mode_t mode = srcstat->st_mode & ~S_IEXEC;
+    /* Issue #6074: We ensure user write access, so we can delete it later
+     * when the source file changes. (On POSIX, this only requires write
+     * access to the directory, on Windows, we need write access to the file
+     * as well)
+     */
+    mode |= _S_IWRITE;
 #else
     mode_t mode = srcstat->st_mode & ~S_IXUSR & ~S_IXGRP & ~S_IXOTH;
 #endif