SoapConnection.send throws UnexpectedErrorFault when querying Contact Id by Email

**com.force.api:force-wsc:40.0.0**

Contact query:
```
SELECT Id FROM Contact WHERE Email='user@example.com'
```

In some cases it throws **UnexpectedErrorFault**

```
com.sforce.soap.enterprise.fault.UnexpectedErrorFault: null
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at java.lang.Class.newInstance(Class.java:442)
at com.sforce.ws.bind.TypeMapper.readSingle(TypeMapper.java:673)
at com.sforce.ws.bind.TypeMapper.readObject(TypeMapper.java:556)
at com.sforce.ws.transport.SoapConnection.parseDetail(SoapConnection.java:236)
at com.sforce.ws.transport.SoapConnection.createException(SoapConnection.java:210)
at com.sforce.ws.transport.SoapConnection.receive(SoapConnection.java:156)
at com.sforce.ws.transport.SoapConnection.send(SoapConnection.java:99)
at com.sforce.soap.enterprise.EnterpriseConnection.query(EnterpriseConnection.java:896)
```

Method `SoapConnection.send()` calls method `SoapConnection.receive()` with specifying the `Transport` parameter which returns `Transport.isSuccessful()` as `false`, so then it calls `SoapConnection.createException()` which ends up with `UnexpectedErrorFault` for some reason.

Please fix it.