It is a difference whether the necesarry driver of a datasource is deployed from CLI/console or from the filesystem via scanner.
If the driver is copied to standalone/deployments the starup failed (drive.jar.deployed state file is available).
If the driver is deployed via console/CLI the startup is correct (see log excerpt)

Tested with postgresql.

== datasource (no other changes to standalone.xml)====
<datasource jta="false" jndi-name="java:jboss/JBTravelDatasource" pool-name="JBTravel" enabled="true" use-ccm="false">
<connection-url>jdbc:postgresql://localhost:5432/postgres</connection-url>
<driver-class>org.postgresql.Driver</driver-class>
<driver>postgresql-9.0-801.jar</driver>
<pool>
<min-pool-size>10</min-pool-size>
<max-pool-size>50</max-pool-size>
<prefill>true</prefill>
</pool>
<security>
<user-name>postgres</user-name>
<password>postgres</password>
</security>
<validation>
<background-validation>false</background-validation>
</validation>
<statement>
<share-prepared-statements>false</share-prepared-statements>
</statement>
</datasource>

============== log with added driver from console ========
17:47:14,548 INFO [org.jboss.as.server.deployment.scanner] (MSC service thread 1-4) JBAS015012: Started FileSystemDeploymentService for directory /srv/eap/6.0.Beta1/standalone/deployments
17:47:14,575 INFO [org.jboss.as.connector.subsystems.datasources] (MSC service thread 1-6) JBAS010400: Bound data source [java:jboss/datasources/ExampleDS]
17:47:14,733 INFO [org.jboss.as.connector.deployers.jdbc] (MSC service thread 1-5) JBAS010404: Deploying non-JDBC-compliant driver class org.postgresql.Driver (version 9.0)
17:47:14,755 INFO [org.jboss.as.connector.subsystems.datasources] (MSC service thread 1-6) JBAS010400: Bound data source [java:jboss/JBTravelDatasource]
17:47:14,793 INFO [org.jboss.as.server] (Controller Boot Thread) JBAS018559: Deployed "postgresql-9.0-801.jar"
17:47:14,801 INFO [org.jboss.as] (Controller Boot Thread) JBAS015874: JBoss EAP 6.0.0.Beta1 (AS 7.1.0.Final-redhat-1) started in 2473ms - Started 157 of 231 services (72 services are passive or on-demand)

========== deployed as file to sa/deployments ====
17:44:11,718 INFO [org.jboss.as.connector.subsystems.datasources] (MSC service thread 1-1) JBAS010400: Bound data source [java:jboss/datasources/ExampleDS]
17:44:11,926 INFO [org.jboss.as.controller] (Controller Boot Thread) JBAS014774: Service status report
JBAS014775: New missing/unsatisfied dependencies:
service jboss.jdbc-driver.postgresql-9_0-801_jar (missing) dependents: [service jboss.data-source.java:jboss/JBTravelDatasource]

17:44:11,935 ERROR [org.jboss.as] (Controller Boot Thread) JBAS015875: JBoss EAP 6.0.0.Beta1 (AS 7.1.0.Final-redhat-1) started (with errors) in 2418ms - Started 135 of 209 services (2 services failed or missing dependencies, 70 services are passive or on-demand)
17:44:11,946 INFO [org.jboss.as.server.deployment] (MSC service thread 1-5) JBAS015876: Starting deployment of "postgresql-9.0-801.jar"
17:44:12,086 INFO [org.jboss.as.connector.deployers.jdbc] (MSC service thread 1-2) JBAS010404: Deploying non-JDBC-compliant driver class org.postgresql.Driver (version 9.0)
17:44:12,107 INFO [org.jboss.as.connector.subsystems.datasources] (MSC service thread 1-3) JBAS010400: Bound data source [java:jboss/JBTravelDatasource]
17:44:12,199 INFO [org.jboss.as.server] (DeploymentScanner-threads - 2) JBAS018559: Deployed "postgresql-9.0-801.jar"
17:44:12,201 INFO [org.jboss.as.controller] (DeploymentScanner-threads - 2) JBAS014774: Service status report
JBAS014776: Newly corrected services:
service jboss.jdbc-driver.postgresql-9_0-801_jar (no longer required)