build/toolbase: only use Getcwd when it didn't fail

Change-Id: I77e155e51d956b32bdcfd216f3852e028f8e0c5a
Reviewed-on: https://review.monogon.dev/c/monogon/+/2996
Reviewed-by: Serge Bazanski <serge@monogon.tech>
Tested-by: Jenkins CI
diff --git a/build/toolbase/workspace.go b/build/toolbase/workspace.go
index 0994ac5..b8582af 100644
--- a/build/toolbase/workspace.go
+++ b/build/toolbase/workspace.go
@@ -30,7 +30,7 @@
 		return p, nil
 	}
 
-	if p, err := os.Getwd(); err != nil && isWorkspace(p) {
+	if p, err := os.Getwd(); err == nil && isWorkspace(p) {
 		return p, nil
 	}