math/big: reintroduce pre-Go 1.14 mention in GCD docs

It was removed in CL 217302 but was intentionally added in CL 217104.

Change-Id: I1a478d80ad1ec4f0a0184bfebf8f1a5e352cfe8c
Reviewed-on: https://go-review.googlesource.com/c/go/+/217941
Reviewed-by: Robert Griesemer <gri@golang.org>

diff --git a/src/math/big/int.go b/src/math/big/int.go
index bec0a81b20bd94eaf616472312b7514b88939182..18f122e953c45a5b314d95d6fff564db02d18fe4 100644 (file)
--- a/src/math/big/int.go
+++ b/src/math/big/int.go
@@ -505,8 +505,8 @@ func (z *Int) Exp(x, y, m *Int) *Int {
 // GCD sets z to the greatest common divisor of a and b and returns z.
 // If x or y are not nil, GCD sets their value such that z = a*x + b*y.
 //
-// a and b may be positive, zero or negative.
-// Regardless of the signs of a and b, z is always >= 0.
+// a and b may be positive, zero or negative. (Before Go 1.14 both had
+// to be > 0.) Regardless of the signs of a and b, z is always >= 0.
 //
 // If a == b == 0, GCD sets z = x = y = 0.
 //