From 24c05c3839ed6e1253b6bfbe88137efdfdde86db Mon Sep 17 00:00:00 2001
From: Michael Abbott <32575566+mcabbott@users.noreply.github.com>
Date: Sun, 7 Nov 2021 19:12:19 -0500
Subject: [PATCH] zip'

---
 src/tangent_types/abstract_zero.jl | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/tangent_types/abstract_zero.jl b/src/tangent_types/abstract_zero.jl
index c14e61c5b..87ac65937 100644
--- a/src/tangent_types/abstract_zero.jl
+++ b/src/tangent_types/abstract_zero.jl
@@ -81,7 +81,11 @@ function _promote_vectors(x::AbstractVector, y::AbstractVector)
     if isconcretetype(T)
         return convert(T, x), convert(T, y)
     else
-        short = map(Base.splat(first ∘ promote), zip(x, y))
+        if VERSION > v"1.4"
+            short = map(first ∘ promote, x, y)
+        else  # on 1.0 and friends, neither map nor zip stop early. So we improvise
+            short = [promote(x[i], y[i])[1] for i in intersect(axes(x, 1), axes(y, 1))]
+        end
         return convert(typeof(short), x), convert(typeof(short), y)
     end
 end