Please merge revision e11ce8ba87952ee2efeb7ed8211801f6cb6d9c9d into dev channel

[pq]

@ricowind @whesse @mit-mit @kasperl

Please merge e11ce8b to dev; this fixes an issue where dartanalyzer falls over with malformed .packages file input (#24126).

[whesse]

Merged in 1.12.0-dev.5.6