strip fully qualified bazel tools path

tentative fix for https://forums.ankiweb.net/t/anki-2-1-50-beta-3/17501/17

tools/bazel

@@ -15,6 +15,7 @@ fi
 # genrule() invocations like //:buildinfo, as they call 'bazel run python', which
 # fails as BAZEL_REAL is not passed to the child process. Work around it by removing
 # the tools folder from the path.
-export PATH=$(echo "$PATH" | sed 's@^.*/tools:@@')
+toolsPath=$(dirname $0)
+export PATH=$(echo "$PATH" | sed "s@${toolsPath}:@@")
 
 exec $BAZEL_REAL $extra_args "$@"