Bug 1767335: Fix mach vendor pattern replacement r=jewilde

Differential Revision: https://phabricator.services.mozilla.com/D145360

media/libdav1d/vcs_version.h

@@ -1,2 +1,2 @@
 /* auto-generated, do not edit */
-#define DAV1D_VERSION "0.9.2-170-g28a9c46"
+#define DAV1D_VERSION "@VCS_TAG@"

python/mozbuild/mozbuild/vendor/vendor_manifest.py

@@ -501,7 +501,7 @@ class VendorManifest(MozbuildObject):
                 replacement = update["with"].replace("{revision}", revision)
                 _replace_in_file(
                     file,
-                    pattern,
+                    update["pattern"],
                     replacement,
                     regex=update["action"] == "replace-in-file",
                 )