config: fix issues with memory-only config file paths

Fixes #5222

cmd/version/version_test.go

@@ -26,12 +26,12 @@ func TestVersionWorksWithoutAccessibleConfigFile(t *testing.T) {
 	}
 	// re-wire
 	oldOsStdout := os.Stdout
-	oldConfigPath := config.ConfigPath
-	config.ConfigPath = path
+	oldConfigPath := config.GetConfigPath()
+	assert.NoError(t, config.SetConfigPath(path))
 	os.Stdout = nil
 	defer func() {
 		os.Stdout = oldOsStdout
-		config.ConfigPath = oldConfigPath
+		assert.NoError(t, config.SetConfigPath(oldConfigPath))
 	}()
 
 	cmd.Root.SetArgs([]string{"version"})