Merge remote branch 'rude/disable-keys-for-postgres-9.0.1' into pg

* rude/disable-keys-for-postgres-9.0.1:
  Cleaner way to extract the Postgres version
  Fix Bug: disable_referential_integrity doesn't work for postgres 9.0.1

activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb

@@ -404,10 +404,7 @@ def session_auth=(user)
       # REFERENTIAL INTEGRITY ====================================
 
       def supports_disable_referential_integrity?() #:nodoc:
-        version = query("SHOW server_version")[0][0].split('.')
-        version[0].to_i >= 8 && version[1].to_i >= 1
-      rescue
-        return false
+        postgresql_version >= 80100
       end
 
       def disable_referential_integrity #:nodoc:
@@ -956,8 +953,12 @@ def postgresql_version
             else
               # Mimic PGconn.server_version behavior
               begin
-                query('SELECT version()')[0][0] =~ /PostgreSQL (\d+)\.(\d+)\.(\d+)/
-                ($1.to_i * 10000) + ($2.to_i * 100) + $3.to_i
+                if query('SELECT version()')[0][0] =~ /PostgreSQL ([0-9.]+)/
+                  major, minor, tiny = $1.split(".")
+                  (major.to_i * 10000) + (minor.to_i * 100) + tiny.to_i
+                else
+                  0
+                end
               rescue
                 0
               end