Seems like not all versions of postgres-drivers contain the string "ERROR"...

Ralf Schlatterbeck · Ralf Schlatterbeck · commit 12da76c5e53a · 2007-08-09T08:58:42.000Z
...in error-messages. In that case creating the database (when it
already exists) fails. This fixes the problem for me.
diff --git a/roundup/backends/back_postgresql.py b/roundup/backends/back_postgresql.py
@@ -1,4 +1,4 @@
-#$Id: back_postgresql.py,v 1.38 2007-06-21 07:35:50 schlatterbeck Exp $
+#$Id: back_postgresql.py,v 1.39 2007-08-09 08:58:42 schlatterbeck Exp $
 #
 # Copyright (c) 2003 Martynas Sklyzmantas, Andrey Lebedev <andrey@micro.lt>
 #
@@ -79,7 +79,7 @@ def pg_command(cursor, command):
         response = str(err).split('\n')[0]
         if response.find('FATAL') != -1:
             raise RuntimeError, response
-        elif response.find('ERROR') != -1:
+        else:
             msgs = [
                 'is being accessed by other users',
                 'could not serialize access due to concurrent update',

Original file line number	Diff line number	Diff line change
`@@ -1,4 +1,4 @@`
`1`		`-#$Id: back_postgresql.py,v 1.38 2007-06-21 07:35:50 schlatterbeck Exp $`
	`1`	`+#$Id: back_postgresql.py,v 1.39 2007-08-09 08:58:42 schlatterbeck Exp $`
`2`	`2`	`#`
`3`	`3`	`# Copyright (c) 2003 Martynas Sklyzmantas, Andrey Lebedev <[email protected]>`
`4`	`4`	`#`
`@@ -79,7 +79,7 @@ def pg_command(cursor, command):`
`79`	`79`	`response = str(err).split('\n')[0]`
`80`	`80`	`if response.find('FATAL') != -1:`
`81`	`81`	`raise RuntimeError, response`
`82`		`- elif response.find('ERROR') != -1:`
	`82`	`+ else:`
`83`	`83`	`msgs = [`
`84`	`84`	`'is being accessed by other users',`
`85`	`85`	`'could not serialize access due to concurrent update',`