I think you version of svn is a bit old. I tried the same in my local box and find it working.
<snip>
sivakumar@sivakumar-laptop:/tmp$ svn export https://xxx/svn/repos/xxx/branches/release/x.0.1.0/build/dummy/
A dummy
A dummy/app0
A dummy/app1
A dummy/app2
Exported revision 43925.
sivakumar@sivakumar-laptop:/tmp$ ls dummy/app2
sivakumar@sivakumar-laptop:/tmp$ cd dummy/app2/
sivakumar@sivakumar-laptop:/tmp/dummy/app2$ ls
sivakumar@sivakumar-laptop:/tmp/support/tomcat$ svn --version
svn, version 1.6.6 (r40053)
compiled Dec 12 2009, 05:04:54
Copyright (C) 2000-2009 CollabNet.
Subversion is open source software, see http://subversion.tigris.org/
This product includes software developed by CollabNet (http://www.Collab.Net/).
The following repository access (RA) modules are available:
* ra_neon : Module for accessing a repository via WebDAV protocol using Neon.
- handles 'http' scheme
- handles 'https' scheme
* ra_svn : Module for accessing a repository using the svn network protocol.
- with Cyrus SASL authentication
- handles 'svn' scheme
* ra_local : Module for accessing a repository on local disk.
- handles 'file' scheme
</snip>
This is the commit, which fixed this problem http://svn.apache.org/viewvc/subversion/trunk/subversion/libsvn_client/export.c?view=log&pathrev=846726
Alternatively you can think of adding some dummy file if you are constrained by the version you are using. BTW, newer svn clients does with with older svn server.