Remove the old cache file when we roll the cache over. This is

to avoid a security problem arising from the way that Zope
changes the effective user id. The first cache file gets created while
Zope is root, so it can't be reopened as nobody.

src/ZEO/ClientCache.py

@@ -144,7 +144,7 @@ file 0 and file 1.
 
 """
 
-__version__ = "$Revision: 1.9 $"[11:-2]
+__version__ = "$Revision: 1.10 $"[11:-2]
 
 import os, tempfile
 from struct import pack, unpack
@@ -323,6 +323,13 @@ class ClientCache:
             self._current=current
             if self._p[current] is not None:
                 # Persistent cache file:
+                # Note that due to permission madness, waaa,
+                # we need to remove the old file before
+                # we open the new one. Waaaaaaaaaa.
+                if self._f[current] is not None:
+                    close(self._f[current])
+                    try: os.remove(self._p[current])
+                    except: pass
                 self._f[current]=open(self._p[current],'w+b')
             else:
                 # Temporary cache file: