cmd/dist: fix typo

Change-Id: Ib5d7f3eadff03070043d52659af4312ee293c586
Reviewed-on: https://go-review.googlesource.com/c/go/+/244817
Reviewed-by: Alberto Donizetti <alb.donizetti@gmail.com>
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/src/cmd/dist/build.go b/src/cmd/dist/build.go
index a817e6f..397b3bb 100644
--- a/src/cmd/dist/build.go
+++ b/src/cmd/dist/build.go
@@ -1209,7 +1209,7 @@
 		}
 		i := strings.Index(s, " start")
 		if i < 0 {
-			log.Fatalf("time log %s does not begin with start line", os.Getenv("GOBULDTIMELOGFILE"))
+			log.Fatalf("time log %s does not begin with start line", os.Getenv("GOBUILDTIMELOGFILE"))
 		}
 		t, err := time.Parse(time.UnixDate, s[:i])
 		if err != nil {