It appears to be an issue with SVN Kit. I've included important references
below followed by the first exception when I was using update and the second
when I was using checkout. The URL I was checking out from was:

https://configuration-data-repository.googlecode.com/svn/trunk/

References:
Reported it on googlecode forum:
http://groups.google.com/group/google-code-hosting/browse_thread/thread/75e6f8633d5ddb8d

Reported it on hudson nabble:
http://www.nabble.com/Cannot-Checkout-or-Update-Google-Code-with-.222-and-.226-td18036320.html

Similar issues with SVNKit:
http://www.nabble.com/REPORT-request-failed-accessing-Sourceforge-Subversion-td14733189.html

Update exception:

Checking out https://configuration-data-repository.googlecode.com/svn/trunk
ERROR: Failed to check out
https://configuration-data-repository.googlecode.com/svn/trunk
org.tmatesoft.svn.core.SVNException: svn: PROPFIND of '/svn/trunk':
502 Bad Gateway (https://configuration-data-repository.googlecode.com)
at
org.tmatesoft.svn.core.internal.wc.SVNErrorManager.error(SVNErrorManager.java:
69)
at
org.tmatesoft.svn.core.internal.io.dav.DAVUtil.findStartingProperties(DAVUtil.java:
126)
at
org.tmatesoft.svn.core.internal.io.dav.DAVUtil.getBaselineProperties(DAVUtil.java:
199)
at
org.tmatesoft.svn.core.internal.io.dav.DAVUtil.getBaselineInfo(DAVUtil.java:
162)
at
org.tmatesoft.svn.core.internal.io.dav.DAVRepository.getLatestRevision(DAVRepository.java:
150)
at
org.tmatesoft.svn.core.wc.SVNBasicClient.getRevisionNumber(SVNBasicClient.java:
348)
at
org.tmatesoft.svn.core.wc.SVNBasicClient.getLocations(SVNBasicClient.java:
462)
at
org.tmatesoft.svn.core.wc.SVNBasicClient.createRepository(SVNBasicClient.java:
418)
at
org.tmatesoft.svn.core.wc.SVNBasicClient.createRepository(SVNBasicClient.java:
382)
at
org.tmatesoft.svn.core.wc.SVNUpdateClient.doCheckout(SVNUpdateClient.java:
305)
at hudson.scm.SubversionSCM$CheckOutTask.invoke(SubversionSCM.java:
418)
at hudson.scm.SubversionSCM$CheckOutTask.invoke(SubversionSCM.java:
357)
at hudson.FilePath.act(FilePath.java:315)
at hudson.scm.SubversionSCM.checkout(SubversionSCM.java:351)
at hudson.scm.SubversionSCM.checkout(SubversionSCM.java:302)
at hudson.model.AbstractProject.checkout(AbstractProject.java:574)
at hudson.model.AbstractBuild
$AbstractRunner.checkout(AbstractBuild.java:251)
at hudson.model.AbstractBuild$AbstractRunner.run(AbstractBuild.java:
225)
at hudson.model.Run.run(Run.java:771)
at hudson.model.Build.run(Build.java:85)
at hudson.model.ResourceController.execute(ResourceController.java:
70)
at hudson.model.Executor.run(Executor.java:82)
Caused by: org.tmatesoft.svn.core.SVNException: svn: PROPFIND of '/svn/
trunk': 502 Bad Gateway (https://configuration-data-
repository.googlecode.com)
at
org.tmatesoft.svn.core.internal.wc.SVNErrorManager.error(SVNErrorManager.java:
55)
at
org.tmatesoft.svn.core.internal.wc.SVNErrorManager.error(SVNErrorManager.java:
40)
at
org.tmatesoft.svn.core.internal.io.dav.DAVUtil.getResourceProperties(DAVUtil.java:
64)
at
org.tmatesoft.svn.core.internal.io.dav.DAVUtil.getStartingProperties(DAVUtil.java:
92)
at
org.tmatesoft.svn.core.internal.io.dav.DAVUtil.findStartingProperties(DAVUtil.java:
114)
... 20 more
Sending e-mails to: shol...@delegata.com
ERROR: Could not connect to SMTP host: localhost, port: 25
javax.mail.MessagingException: Could not connect to SMTP host:
localhost, port: 25;
nested exception is:
java.net.ConnectException: Connection refused
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:
1282)
at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:
370)
at javax.mail.Service.connect(Service.java:275)
at javax.mail.Service.connect(Service.java:156)
at javax.mail.Service.connect(Service.java:105)
at javax.mail.Transport.send0(Transport.java:168)
at javax.mail.Transport.send(Transport.java:98)
at hudson.tasks.MailSender.execute(MailSender.java:75)
at hudson.tasks.Mailer._perform(Mailer.java:75)
at hudson.tasks.Mailer.perform(Mailer.java:69)
at
hudson.tasks.BuildStepCompatibilityLayer.perform(BuildStepCompatibilityLayer.java:
33)
at hudson.model.AbstractBuild
$AbstractRunner.performAllBuildStep(AbstractBuild.java:309)
at hudson.model.AbstractBuild
$AbstractRunner.performAllBuildStep(AbstractBuild.java:297)
at hudson.model.Build$RunnerImpl.post2(Build.java:118)
at hudson.model.AbstractBuild$AbstractRunner.post(AbstractBuild.java:
282)
at hudson.model.Run.run(Run.java:789)
at hudson.model.Build.run(Build.java:85)
at hudson.model.ResourceController.execute(ResourceController.java:
70)
at hudson.model.Executor.run(Executor.java:82)
Caused by: java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:
195)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:519)
at java.net.Socket.connect(Socket.java:469)
at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:
232)
at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:189)
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:
1250)
... 18 more
finished: FAILURE

Checkout Exception:

ERROR: Failed to check out
https://configuration-data-repository.googlecode.com/svn/trunk
org.tmatesoft.svn.core.SVNException: svn: REPORT request failed on '/
svn/!svn/vcc/default'
svn: Processing REPORT request response failed: XML document
structures must start and end within the same entity. (/svn/!svn/vcc/
default)
at
org.tmatesoft.svn.core.internal.wc.SVNErrorManager.error(SVNErrorManager.java:
55)
at
org.tmatesoft.svn.core.internal.wc.SVNErrorManager.error(SVNErrorManager.java:
40)
at
org.tmatesoft.svn.core.internal.io.dav.http.HTTPConnection.request(HTTPConnection.java:
545)
at
org.tmatesoft.svn.core.internal.io.dav.http.HTTPConnection.request(HTTPConnection.java:
246)
at
org.tmatesoft.svn.core.internal.io.dav.http.HTTPConnection.request(HTTPConnection.java:
234)
at
org.tmatesoft.svn.core.internal.io.dav.DAVConnection.doReport(DAVConnection.java:
219)
at
org.tmatesoft.svn.core.internal.io.dav.DAVConnection.doReport(DAVConnection.java:
211)
at
org.tmatesoft.svn.core.internal.io.dav.DAVRepository.update(DAVRepository.java:
610)
at
org.tmatesoft.svn.core.wc.SVNUpdateClient.doUpdate(SVNUpdateClient.java:
162)
at
org.tmatesoft.svn.core.wc.SVNUpdateClient.doCheckout(SVNUpdateClient.java:
325)
at hudson.scm.SubversionSCM$CheckOutTask.invoke(SubversionSCM.java:
418)
at hudson.scm.SubversionSCM$CheckOutTask.invoke(SubversionSCM.java:
357)
at hudson.FilePath.act(FilePath.java:315)
at hudson.scm.SubversionSCM.checkout(SubversionSCM.java:351)
at hudson.scm.SubversionSCM.checkout(SubversionSCM.java:302)
at hudson.model.AbstractProject.checkout(AbstractProject.java:574)
at hudson.model.AbstractBuild
$AbstractRunner.checkout(AbstractBuild.java:251)
at hudson.model.AbstractBuild$AbstractRunner.run(AbstractBuild.java:
225)
at hudson.model.Run.run(Run.java:771)
at hudson.model.Build.run(Build.java:85)
at hudson.model.ResourceController.execute(ResourceController.java:
70)
at hudson.model.Executor.run(Executor.java:85)
Sending e-mails to: shol...@delegata.com
finished: FAILURE