Make default values fall through in switch

Bug 19093.  Previously {{#switch:foo|bar|#default=baz}} would behave
differently from {{#switch:foo|#default|bar=baz}}, even though they'd
behave identically if "#default" was replaced by "foo".

I changed switchObj but not switchHook.  In testing, switchObj was the
only method that seemed to be used, and I didn't want to make untested
changes to switchHook, so if that's used, the behavior may remain in
some cases.  It seems like code is duplicated between them -- whatever
the difference is, that should probably be factored out.

This passes all existing parser tests for #switch, of which there are
none, so don't blame me if it breaks something.  ;)

ParserFunctions_body.php

@@ -187,7 +187,7 @@ class ExtParserFunctions {
 			return '';
 		}
 		$primary = trim( $frame->expand( array_shift( $args ) ) );
-		$found = false;
+		$found = $defaultFound = false;
 		$default = null;
 		$lastItemHadNoEquals = false;
 		$mwDefault =& MagicWord::get( 'default' );
@@ -209,7 +209,7 @@ class ExtParserFunctions {
 					if ( $test == $primary ) {
 						# Found a match, return now
 						return trim( $frame->expand( $valueNode ) );
-					} elseif ( $mwDefault->matchStartAndRemove( $test ) ) {
+					} elseif ( $defaultFound || $mwDefault->matchStartAndRemove( $test ) ) {
 						$default = $valueNode;
 					} # else wrong case, continue
 				}
@@ -220,6 +220,8 @@ class ExtParserFunctions {
 				$test = trim( $frame->expand( $valueNode ) );
 				if ( $test == $primary ) {
 					$found = true;
+				} elseif ( $mwDefault->matchStartAndRemove( $test ) ) {
+					$defaultFound = true;
 				}
 			}
 		}

funcsParserTests.txt

@@ -41,3 +41,14 @@ Time test after the 2038 32-bit Apocalype
 <p>2061
 </p>
 !! end
+
+!! test
+Bug 19093: Default values don't fall through in switch
+!! input
+<{{#switch: foo | bar | #default = DEF }}>
+<{{#switch: foo | #default | bar = DEF }}>
+!! result
+<p>&lt;DEF&gt;
+&lt;DEF&gt;
+</p>
+!! end