"promises" plug-in not functioning when using vcapServices option to initialize Cloudant

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Bug Description

When initializing Cloudant using the vcapServices option, the "promises" plug-in does not seem to function. When initializing cloudant using url:, the plugin DOES work. In both cases, the Cloudant database successfully connects.

1. Steps to reproduce and the simplest code sample possible to demonstrate the issue

The following code DOES work:

let cloud_DB = new Cloudant({url:cloudand_url, plugins: 'promises' }, (err, cloudant, reply) => {
appEnv.services }, (err, cloudant, reply) => {
  if (err) {
    throw (err)
    console.log("Error creating cloudant " + err);
  }
    console.log("made DB");
});

cloud_DB.db.use('database_name').info().then((body) => {
  console.log(`got info <from a promise>: ${body}`);
})

the following code DOES NOT work:

let cloud_DB = new Cloudant({vcapInstanceName:'Cloudant-d2', vcapServices: appEnv.services, plugins: 'promises' }, (err, cloudant, reply) => {
  if (err) {
    throw (err)
    console.log("Error creating cloudant " + err);
  }
    console.log("made DB");
});

cloud_DB.db.use('database_name').info().then((body) => {
  console.log(`got info <from a promise>: ${body}`);
})

It is fair to point out that I am passing appEvn.services to vcapServices. This appEvn uses cfenv to get the vcap services or a local copy, if the code is local.

2. What you expected to happen

In both cases, I would expect to see in the console:

made DB
got info <from a promise>: [object object]

3. What actually happened

In the first example, I see what I expect.

In the second example, I see made DB but then receive a TypeError: cloud_DB.db.use(...).info(...).then is not a function

note that if I make the same call without using promises, it works in both cases. Example:

cloud_DB.db.use('database_name').info((err, body) => {
    if(err) console.log("DB info Error " + err);
    if(body){
      console.log("DB info " + body);
    }
});

Environment details

@cloudant/cloudant version

2.4.0
Node.js version

9.8.0

cloudant / nodejs-cloudant