[FIXED JENKINS-12995] specify absolute path of build script.

src/main/java/hudson/plugins/phing/PhingBuilder.java

@@ -157,7 +157,7 @@ public boolean perform(AbstractBuild<?, ?> build, Launcher launcher, BuildListen
            return false;
        }

        args.add("-buildfile", buildScript.getName());
        args.add("-buildfile", buildScript.getRemote());

        // Targets
        String expandedTargets = Util.replaceMacro(env.expand(targets), vr);
@@ -185,7 +185,8 @@ public boolean perform(AbstractBuild<?, ?> build, Launcher launcher, BuildListen
        // Working Directory
        // since 0.9
        FilePath working = useModuleRoot ? build.getModuleRoot() : buildScript.getParent();

        listener.getLogger().println(Messages.Phing_WorkingDirectory(working));

        final long startTime = System.currentTimeMillis();
        try {
            PhingConsoleAnnotator pca = new PhingConsoleAnnotator(listener.getLogger(), build.getCharset());

src/main/resources/hudson/plugins/phing/Messages.properties

@@ -8,3 +8,4 @@ Phing.ProjectConfigNeeded = Maybe you need to configure the job to choose one of
Phing.NotAPHPCommand = {0} doesn''t exists.
Phing.DirectoryNotAllowed = {0} seems to be directory.
Phing.NotFoundABuildScript = buildfile ''{0}'' not found.
Phing.WorkingDirectory = use ''{0}'' as a working directory. 

src/main/resources/hudson/plugins/phing/Messages_ja.properties

@@ -8,3 +8,4 @@ Phing.ProjectConfigNeeded = \u30a4\u30f3\u30b9\u30c8\u30fc\u30eb\u3057\u305fPhin
Phing.NotAPHPCommand = {0}\u304c\u5b58\u5728\u3057\u307e\u305b\u3093\u3002
Phing.DirectoryNotAllowed= {0} \u306f\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u3067\u3059\u3002
Phing.NotFoundABuildScript = \u30d3\u30eb\u30c9\u30d5\u30a1\u30a4\u30eb''{0}''\u304c\u5b58\u5728\u3057\u307e\u305b\u3093\u3002
Phing.WorkingDirectory = ''{0}'' \u3092\u30ef\u30fc\u30ad\u30f3\u30b0\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u3068\u3057\u3066\u4f7f\u7528\u3057\u307e\u3059\u3002 

src/main/resources/hudson/plugins/phing/PhingBuilder/config.jelly

@@ -24,7 +24,7 @@
        </f:entry>
        <f:entry title="">
            <label>
              <f:checkbox name="phingBuilder.useModuleRoot" checked="${instance.useModuleRoot}" />
              <f:checkbox name="phingBuilder.useModuleRoot" default="true" checked="${instance.useModuleRoot}" />
              ${%Use ModuleRoot as working directory}
            </label>
        </f:entry>