diff -up thunderbird-60.0/build/moz.configure/init.configure.triplet-failure thunderbird-60.0/build/moz.configure/init.configure
--- thunderbird-60.0/build/moz.configure/init.configure.triplet-failure	2018-10-02 14:13:04.276835572 +0200
+++ thunderbird-60.0/build/moz.configure/init.configure	2018-10-02 14:13:18.921865210 +0200
@@ -577,7 +577,13 @@ def split_triplet(triplet, allow_unknown
     # There is also a quartet form:
     #   CPU_TYPE-MANUFACTURER-KERNEL-OPERATING_SYSTEM
     # But we can consider the "KERNEL-OPERATING_SYSTEM" as one.
-    cpu, manufacturer, os = triplet.split('-', 2)
+    parts = triplet.split('-', 2)
+    if len(parts) == 3:
+        cpu, _, os = parts
+    elif len(parts) == 2:
+        cpu, os = parts
+    else:
+        die("Unexpected triplet string: %s" % triplet)
 
     # Autoconf uses config.sub to validate and canonicalize those triplets,
     # but the granularity of its results has never been satisfying to our