diff -Nru python-central-0.6.15/debian/changelog python-central-0.6.16/debian/changelog
--- python-central-0.6.15/debian/changelog	2010-03-31 15:52:37.000000000 +0200
+++ python-central-0.6.16/debian/changelog	2010-04-07 10:13:32.000000000 +0200
@@ -1,3 +1,12 @@
+python-central (0.6.16) unstable; urgency=low
+
+  * pycentral cleanup-pkgprepare-updates:
+    - Try to use dlocate instead of dpkg -S.
+    - Don't try to remove emptied directories more than once (Piotr
+      Ozarowski).
+
+ -- Matthias Klose <doko@debian.org>  Wed, 07 Apr 2010 08:10:12 +0200
+
 python-central (0.6.15) experimental; urgency=low
 
   [ Matthias Klose ]
diff -Nru python-central-0.6.15/dh_pycentral.1 python-central-0.6.16/dh_pycentral.1
--- python-central-0.6.15/dh_pycentral.1	2010-03-31 16:13:13.000000000 +0200
+++ python-central-0.6.16/dh_pycentral.1	2010-04-07 10:15:09.000000000 +0200
@@ -1,4 +1,4 @@
-.\" Automatically generated by Pod::Man 2.22 (Pod::Simple 3.07)
+.\" Automatically generated by Pod::Man 2.1801 (Pod::Simple 3.05)
 .\"
 .\" Standard preamble:
 .\" ========================================================================
diff -Nru python-central-0.6.15/pycentral.py python-central-0.6.16/pycentral.py
--- python-central-0.6.15/pycentral.py	2010-03-31 15:50:12.000000000 +0200
+++ python-central-0.6.16/pycentral.py	2010-04-07 10:17:14.000000000 +0200
@@ -18,7 +18,7 @@
 
 shared_base = '/usr/share/pycentral/'
 shared_base2 = '/usr/share/pyshared/'
-pycentral_version = '0.6.15'
+pycentral_version = '0.6.16'
 req_pycentral_version = '0.6.15'
 
 
@@ -1879,6 +1879,10 @@
 
 register_action(ActionUpdateDefault)
 
+
+class DlocateError(Exception):
+    pass
+
 class ActionCleanupPkgPrepareUpdates(Action):
     name = 'cleanup-pkgprepare-updates'
     help = 'cleanup dangling symlinks and byte code files'
@@ -1903,6 +1907,7 @@
         
         # then remove those not belonging to any package
         dirs = []
+        removed = 0
         for fn in unowned:
             try:
                 os.unlink(fn + 'c')
@@ -1911,7 +1916,9 @@
                 pass
             try:
                 os.unlink(fn)
-                dirs.append(os.path.dirname(fn))
+                removed += 1
+                if not os.path.dirname(fn) in dirs:
+                    dirs.append(os.path.dirname(fn))
             except OSError, e:
                 self.error("error removing dangling symlink: %s" % str(e),
                            go_on=True)
@@ -1924,7 +1931,8 @@
         if len(packaged) > 0:
             for fn in packaged:
                 self.warn('dangling symlink owned by package: %s' % fn)
-        self.warn('removed %d dangling symlinks not owned by any package')
+        if removed:
+            self.warn('removed %d dangling symlinks not owned by any package' % removed)
         return self.errors_occured
 
     def check_dangling_links(self):
@@ -1950,28 +1958,68 @@
                     dangling.append(link)
         return dangling
 
-    def links_in_packages(self, links):
+    def locate(self, arg_list, cmd_list):
         from subprocess import PIPE, Popen
-        def chunks(l, n):
-            return [l[i:i+n] for i in range(0, len(l), n)]
-        packaged = set()
-        notfound = 0
-        for arg_list in chunks(links, 50):
-            (stdout, stderr) = Popen(["dpkg","-S"] + arg_list,
-                                     env={"LANG" : "C"},
-                                     stdout=PIPE, stderr=PIPE).communicate()
-            if stdout:
-                for line in map(string.strip, stdout.split("\n")):
-                    if line == '': continue
-                    fn = line.split(':', 1)[1][1:]
-                    if fn in arg_list:
-                        packaged.add(fn)
-            if stderr:
-                for line in map(string.strip, stderr.split("\n")):
-                    if line == '': continue
-                    fn = line.split(':', 1)[1][1:-11]
-                    notfound += 1
-        return packaged
+        (stdout, stderr) = Popen(cmd_list + arg_list,
+                                 env={"LANG" : "C"},
+                                 shell=False,
+                                 stdout=PIPE, stderr=PIPE).communicate()
+        if stdout:
+            for line in map(string.strip, stdout.split("\n")):
+                # dlocate writes error messages to stdout
+                if line.startswith('dlocate: unknown option'):
+                    raise DlocateError
+                if line == '': continue
+                fn = line.split(':', 1)[1][1:]
+                if fn in arg_list:
+                    self.packaged.add(fn)
+        if stderr:
+            for line in map(string.strip, stderr.split("\n")):
+                if line.startswith('dlocate: unknown option'):
+                    raise DlocateError
+                if line == '': continue
+                fn = line.split(':', 1)[1][1:-11]
+                self.notfound += 1
+
+    def links_in_packages(self, links):
+        def chunks(l):
+            if 'SC_ARG_MAX' in os.sysconf_names:
+                chunk_max = os.sysconf('SC_ARG_MAX')
+            else:
+                chunk_max = 16384
+            chunk_max -= reduce(lambda x,y: x+y,
+                                [len(k)+len(v)+3 for k,v in os.environ.items()])
+            chunk_max -= 20
+            chunk = []
+            lchunk = 0
+            all_chunks = []
+            for i in l:
+                if lchunk + len(i)+1 > chunk_max:
+                    all_chunks.append(chunk)
+                    chunk = []
+                    lchunk = 0
+                chunk.append(i)
+                lchunk += len(i) + 1
+            if chunk:
+                all_chunks.append(chunk)
+            return all_chunks
+
+        self.packaged = set()
+        self.notfound = 0
+        all_chunks = chunks(links)
+        arg_list = all_chunks[0]
+        if os.path.exists('/usr/bin/dlocate'):
+            cmd_list = ["dlocate","--fixed-strings"]
+        else:
+            cmd_list = ["dpkg","-S"]
+        try:
+            self.locate(arg_list, cmd_list)
+        except DlocateError:
+            cmd_list = ["dpkg","-S"]
+            self.locate(arg_list, cmd_list)
+        for arg_list in all_chunks[1:]:
+            self.locate(arg_list, cmd_list)
+        return self.packaged
 
 register_action(ActionCleanupPkgPrepareUpdates)