Error during MongoDB initialization

In my configuration, there's a NullPointerException when doing
new DocumentMK.Builder().setMongoDB(db)
due to the "serverStatus" command not returning the expected object.

Here's my stacktrace:

java.lang.NullPointerException
at java.util.regex.Matcher.getTextLength(Matcher.java:1283)
at java.util.regex.Matcher.reset(Matcher.java:309)
at java.util.regex.Matcher.<init>(Matcher.java:229)
at java.util.regex.Pattern.matcher(Pattern.java:1093)
at org.apache.jackrabbit.oak.plugins.document.mongo.MongoDocumentStore.checkVersion(MongoDocumentStore.java:305)
at org.apache.jackrabbit.oak.plugins.document.mongo.MongoDocumentStore.<init>(MongoDocumentStore.java:236)
at org.apache.jackrabbit.oak.plugins.document.DocumentMK$Builder.setMongoDB(DocumentMK.java:633)
at org.apache.jackrabbit.oak.plugins.document.DocumentMK$Builder.setMongoDB(DocumentMK.java:655)

The "serverStatus" command in MongoDocumentStore constructor returns:

{ "ok" : 0.0 , "errmsg" : "not authorized on <mydatabase> to execute command

" , "code" : 13}

Prior to version 1.5.6, "buildInfo" command was called instead, which happens to work from a mongo shell, while "serverStatus" doesn't.

Seems related to OAK-4111.