Google App Engine Deploy Error

Ran into a very confusion error when deploying a new app to App Engine.

------------ Deploying frontend ------------

Preparing to deploy:

Created staging directory at: 'C:\Users\Carl\AppData\Local\Temp\appcfg8392684210541476644.tmp'

Scanning for jsp files.

Scanning files on local disk.

Initiating update.

com.google.appengine.tools.admin.HttpIoException: Error posting to URL: https://appengine.google.com/api/appversion/create?app_id=git-app&version=1&

400 Bad Request

Error when loading application configuration:Unable to assign value 'email' to attribute 'url':Value 'email' for url does not match expression '^(?:(?!\^)/.*|\..*|(\(.).*(?!\$).)$'

Debugging information may be found in C:\Users\Carl\AppData\Local\Temp\appengine-deploy1202454373832605151.log

By chance I found that a servlet url-pattern didn't start with slash.

<url-pattern>/email</url-pattern> 

Full stacktrace:
Unable to update:
com.google.appengine.tools.admin.HttpIoException: Error posting to URL: https://appengine.google.com/api/appversion/create?app_id=git-app&version=1&
400 Bad Request
Error when loading application configuration:Unable to assign value 'email' to attribute 'url':Value 'email' for url does not match expression '^(?:(?!\^)/.*|\..*|(\(.).*(?!\$).)$'

at com.google.appengine.tools.admin.AbstractServerConnection.send1(AbstractServerConnection.java:303)
at com.google.appengine.tools.admin.AbstractServerConnection.send(AbstractServerConnection.java:254)
at com.google.appengine.tools.admin.AbstractServerConnection.post(AbstractServerConnection.java:233)
at com.google.appengine.tools.admin.LoggingClientDeploySender.send(LoggingClientDeploySender.java:47)
at com.google.appengine.tools.admin.AppVersionUpload.send(AppVersionUpload.java:1100)
at com.google.appengine.tools.admin.AppVersionUpload.beginTransaction(AppVersionUpload.java:735)
at com.google.appengine.tools.admin.AppVersionUpload.uploadFilesTransaction(AppVersionUpload.java:174)
at com.google.appengine.tools.admin.AppVersionUpload.doUpload(AppVersionUpload.java:151)
at com.google.appengine.tools.admin.AppAdminImpl.doUpdate(AppAdminImpl.java:474)
at com.google.appengine.tools.admin.AppAdminImpl.update(AppAdminImpl.java:55)
at com.google.appengine.eclipse.core.proxy.AppEngineBridgeImpl.deploy(AppEngineBridgeImpl.java:433)
at com.google.appengine.eclipse.core.deploy.DeployProjectJob.runInWorkspace(DeployProjectJob.java:158)
at org.eclipse.core.internal.resources.InternalWorkspaceJob.run(InternalWorkspaceJob.java:38)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)