[dev.boringcrypto] all: merge master into dev.boringcrypto

Change-Id: Ic5f71c04f08c03319c043f35be501875adb0a3b0

1 files changed, 10 insertions, 2 deletions

diff --git a/src/cmd/go/internal/base/env.go b/src/cmd/go/internal/base/env.go
index 5f2665d2367..2f47300f2ec 100644
--- a/src/cmd/go/internal/base/env.go
+++ b/src/cmd/go/internal/base/env.go
@@ -4,12 +4,20 @@
 
 package base
 
+import (
+	"fmt"
+	"path/filepath"
+)
+
 // AppendPWD returns the result of appending PWD=dir to the environment base.
 //
 // The resulting environment makes os.Getwd more efficient for a subprocess
 // running in dir.
 func AppendPWD(base []string, dir string) []string {
-	// Internally we only use absolute paths, so dir is absolute.
-	// Even if dir is not absolute, no harm done.
+	// POSIX requires PWD to be absolute.
+	// Internally we only use absolute paths, so dir should already be absolute.
+	if !filepath.IsAbs(dir) {
+		panic(fmt.Sprintf("AppendPWD with relative path %q", dir))
+	}
 	return append(base, "PWD="+dir)
 }