I hit this when doing a reintegrate merge with svn 1.8.3 (tortoisesvn 1.8.2). I repeated the operation with svn 1.7.8 and it did not occur. The following section in the STATUS file looks highly relevant:
Allow compiling against serf 1.3 and later on Windows
Serf 1.3 brings a lot of fixes that we need for 1.8.x stability.
The dependency handling on Windows was updated for 1.9+, so this
needs a specific backport patch (r1517123)
+1: rhuijben, brane