build from source fails because of wrong class file version of servlet-api-3.0.20100224

even when I remove the servlet-api package from local maven repository (forcing a new download) I got following error message:

[INFO] ------------------------------------------------------------------------
[INFO] Building Jetty :: Continuation 7.4.4-SNAPSHOT
[INFO] ------------------------------------------------------------------------
Downloading: http://oss.sonatype.org/content/groups/jetty/org/mortbay/jetty/servlet-api/3.0.20100224/servlet-api-3.0.20100224.pom
Downloaded: http://oss.sonatype.org/content/groups/jetty/org/mortbay/jetty/servlet-api/3.0.20100224/servlet-api-3.0.20100224.pom
Downloading: http://oss.sonatype.org/content/groups/jetty/org/mortbay/jetty/servlet-api/3.0.20100224/servlet-api-3.0.20100224.jar
Downloaded: http://oss.sonatype.org/content/groups/jetty/org/mortbay/jetty/servlet-api/3.0.20100224/servlet-api-3.0.20100224.jar
[INFO]
[INFO] — build-helper-maven-plugin:1.5:parse-version (set-osgi-version) @ jetty-continuation —
[INFO]
[INFO] — maven-enforcer-plugin:1.0:enforce (enforce-java) @ jetty-continuation —
[INFO]
[INFO] — maven-remote-resources-plugin:1.2:process (default) @ jetty-continuation —
[INFO] Setting property: classpath.resource.loader.class => 'org.codehaus.plexus.velocity.ContextClassLoaderResourceLoader'.
[INFO] Setting property: velocimacro.messages.on => 'false'.
[INFO] Setting property: resource.loader => 'classpath'.
[INFO] Setting property: resource.manager.logwhenfound => 'false'.
[INFO]
[INFO] — maven-resources-plugin:2.5:resources (default-resources) @ jetty-continuation —
[debug] execute contextualize
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory \devel\jetty-7-eclipse\jetty-continuation\src\main\resources
[INFO] Copying 1 resource
[INFO]
[INFO] — maven-compiler-plugin:2.3.2:compile (default-compile) @ jetty-continuation —
[INFO] Compiling 8 source files to \devel\jetty-7-eclipse\jetty-continuation\target\classes
[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR :
[INFO] -------------------------------------------------------------
[ERROR] \devel\jetty-7-eclipse\jetty-continuation\src\main\java\org\eclipse\jetty\continuation\ContinuationListener.java:[6,-1] cannot access javax.servlet.ServletRequestListener
bad class file: \tools\.m2\repository\org\mortbay\jetty\servlet-api\3.0.20100224\servlet-api-3.0.20100224.jar(javax/servlet/ServletRequestListener.class)
class file has wrong version 50.0, should be 49.0
[INFO] 1 error