NPE in release:perform when specifying svn tag as param

When executing release:perform and specifying the Svn tag via the 'connectionUrl' parameter, the execution fails with a NullPointerException. This happens for an execution without an existing Maven project (e.g. in an empty directory).

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-release-plugin:2.5:perform (default-cli) on project standalone-pom: Execution default-cli of goal org.apache.maven.plugins:maven-release-plugin:2.5:perform failed. NullPointerException -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-release-plugin:2.5:perform (default-cli) on project standalone-pom: Execution default-cli
of goal org.apache.maven.plugins:maven-release-plugin:2.5:perform failed.
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:225)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:60)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
at java.lang.reflect.Method.invoke(Method.java:611)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)
Caused by: org.apache.maven.plugin.PluginExecutionException: Execution default-cli of goal org.apache.maven.plugins:maven-release-plugin:2.5:perform failed.
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:110)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
... 19 more
Caused by: java.lang.NullPointerException
at org.apache.maven.shared.release.util.ReleaseUtil.getCommonBasedir(ReleaseUtil.java:210)
at org.apache.maven.shared.release.util.ReleaseUtil.getCommonBasedir(ReleaseUtil.java:200)
at org.apache.maven.shared.release.phase.CheckoutProjectFromScm.performCheckout(CheckoutProjectFromScm.java:230)
at org.apache.maven.shared.release.phase.CheckoutProjectFromScm.execute(CheckoutProjectFromScm.java:131)
at org.apache.maven.shared.release.DefaultReleaseManager.perform(DefaultReleaseManager.java:429)
at org.apache.maven.shared.release.DefaultReleaseManager.perform(DefaultReleaseManager.java:381)
at org.apache.maven.plugins.release.PerformReleaseMojo.execute(PerformReleaseMojo.java:177)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
... 20 more