We're getting a lot of timeout errors while activation extensions for our SC webstore. We have around 6 custom extensions and a custom theme. The error on the Extension Manager screen says "Job execution time exceeded. The job has been IN_PROGRESS for more than 15 minutes.". But we also get an e-mail within a few minutes saying so:

{
  "type": "error.SuiteScriptError",
  "name": "Invalid job state transition",
  "message": "From ERROR to DONE",
  "stack": [
    "createError(N/error)",
    "updateToProcessState(/SuiteBundles/Bundle 317001/ExtensionMechanism.Server/Helpers/JobToProcessHelperSS2.js:312)",
    "<anonymous>(/SuiteBundles/Bundle 317001/ExtensionMechanism.Server/Helpers/JobToProcessHelperSS2.js:378)",
    "<anonymous>(/SuiteBundles/Bundle 317001/third_parties/underscore.js:5)",
    "setJobsData(/SuiteBundles/Bundle 317001/ExtensionMechanism.Server/Helpers/JobToProcessHelperSS2.js:376)",
    "summarize(/SuiteBundles/Bundle 317001/ExtensionMechanism.Server/JobToProcess/ManifestLoaderMapReduce.js:175)"
  ],
  "cause": {
    "type": "internal error",
    "code": "Invalid job state transition",
    "details": "From ERROR to DONE",
    "userEvent": null,
    "stackTrace": [
      "createError(N/error)",
      "updateToProcessState(/SuiteBundles/Bundle 317001/ExtensionMechanism.Server/Helpers/JobToProcessHelperSS2.js:312)",
      "<anonymous>(/SuiteBundles/Bundle 317001/ExtensionMechanism.Server/Helpers/JobToProcessHelperSS2.js:378)",
      "<anonymous>(/SuiteBundles/Bundle 317001/third_parties/underscore.js:5)",
      "setJobsData(/SuiteBundles/Bundle 317001/ExtensionMechanism.Server/Helpers/JobToProcessHelperSS2.js:376)",
      "summarize(/SuiteBundles/Bundle 317001/ExtensionMechanism.Server/JobToProcess/ManifestLoaderMapReduce.js:175)"
    ],
    "notifyOff": false
  },
  "id": "",
  "notifyOff": false,
  "userFacing": false
}