line 227: assertion failed (svn_dirent_is_absolute(dir_abspath)) In file 'D:\Development\SVN\Releases\TortoiseSVN-1.9.0\ext\subversion\subversion\libsvn_client\cleanup.c'

Received dialog box:
---------------------------
Subversion Exception!
---------------------------
Subversion encountered a serious problem.
Please take the time to report this on the Subversion mailing list
with as much information as possible about what
you were trying to do.
But please first search the mailing list archives for the error message
to avoid reporting the same problem repeatedly.
You can find the mailing list archives at
http://subversion.apache.org/mailing-lists.html

Subversion reported the following
(you can copy the content of this dialog
to the clipboard using Ctrl-C):

In file
 
'D:\Development\SVN\Releases\TortoiseSVN-1.9.0\ext\subversion\subversion\libsvn_client\cleanup.c'
 line 227: assertion failed (svn_dirent_is_absolute(dir_abspath))
---------------------------
OK
---------------------------

followed by
---------------------------
TortoiseSVN
---------------------------
Cleanup failed to process the following paths:
D:\Nationwide\PolicyCenter804_dev\modules\configuration
sqlite[S5]: database is locked, executing statement 'PRAGMA
 case_sensitive_like=1;PRAGMA synchronous=OFF;PRAGMA
 recursive_triggers=ON;PRAGMA foreign_keys=OFF;PRAGMA locking_mode =
 NORMAL;PRAGMA journal_mode = TRUNCATE;'
Another process is blocking the working copy database, or the underlying
filesystem does not support file locking; if the working copy is on a
network filesystem, make sure file locking has been enabled on the file
server.
---------------------------
OK
---------------------------

Using...
TortoiseSVN 1.9.0, Build 26652 - 64 Bit , 2015/08/03 19:33:09
Subversion 1.9.0, -release
apr 1.5.2
apr-util 1.5.4
serf 1.3.8
OpenSSL 1.0.2d 9 Jul 2015
zlib 1.2.8
SQLite 3.8.11.1

Doing...
Clean up, with these options:

After doing an Update (after returning from a week long Thanksgiving
vacation) and resolving conflicts in two files. Tortoise reported some
file locking problems, during this process.

Rebooted and did "Tortoise SVN -> Clean up..." again, and everything seems
to be just fine.

So I cannot reproduce the problem. And I don't know what might have caused
it.

Looks like the same error as reported in this post:
http://svn.haxx.se/users/archive-2015-10/0062.shtml

Similar to (but probably not the same as) this post:
http://svn.haxx.se/users/archive-2015-10/0100.shtml