mongo::fromjson can't parse this simple json on a linux system with locale setting LC_NUMERIC=de_DE.UTF-8:

{
    "test1": 1,
    "test2": 1
}

parsing fails with the following error message:

terminate called after throwing an instance of 'mongo::MsgAssertionException'
  what():  code FailedToParse: FailedToParse: Expecting '}' or ',': offset:17 of:{
    "test1": 1,
    "test2": 1
}

Then the doSaslX functions 

This error is caused by JParse::number's usage of strtod which may be locale specific and in that cause don't parse according to the json syntax but by some other rules.

The code already points to SERVER-11920 in comments.

This is with the most recent commit on the legacy branch (2e86826)