Fix error PG.version_string(true)

The PG::REVISION was removed in commit eb25f07 but it was still used in this class method.

Fixes #419

lib/pg.rb

@@ -56,11 +56,11 @@ class NotAllCopyDataRetrieved < PG::Error
 	class NotInBlockingMode < PG::Error
 	end
 
-	### Get the PG library version. If +include_buildnum+ is +true+, include the build ID.
-	def self::version_string( include_buildnum=false )
-		vstring = "%s %s" % [ self.name, VERSION ]
-		vstring << " (build %s)" % [ REVISION[/: ([[:xdigit:]]+)/, 1] || '0' ] if include_buildnum
-		return vstring
+	# Get the PG library version.
+	#
+	# +include_buildnum+ is no longer used and any value passed will be ignored.
+	def self::version_string( include_buildnum=nil )
+		return "%s %s" % [ self.name, VERSION ]
 	end
 
 

spec/pg_spec.rb

@@ -12,6 +12,13 @@
 		expect( PG.library_version ).to be >= 90100
 	end
 
+	it "can format the pg version" do
+		expect( PG.version_string ).to be_an( String )
+		expect( PG.version_string ).to match(/PG \d+\.\d+\.\d+/)
+		expect( PG.version_string(true) ).to be_an( String )
+		expect( PG.version_string(true) ).to match(/PG \d+\.\d+\.\d+/)
+	end
+
 	it "can select which of both security libraries to initialize" do
 		# This setting does nothing here, because there is already a connection
 		# to the server, at this point in time.