Index: MimeMagic.php
===================================================================
--- MimeMagic.php	(revision 55559)
+++ MimeMagic.php	(working copy)
@@ -474,6 +474,7 @@
 		 * Warning: this is a heuristic, and won't match a file with a lot of non-PHP before.
 		 * It will also match text files which could be PHP. :)
 		 */
+		$phpmatch = false;
 		if( ( strpos( $head, '<?php' ) !== false ) ||
 		    ( strpos( $head, '<? ' ) !== false ) ||
 		    ( strpos( $head, "<?\n" ) !== false ) ||
@@ -486,8 +487,19 @@
 		    ( strpos( $head, "<\x00?\x00\t" ) !== false ) ||
 		    ( strpos( $head, "<\x00?\x00=" ) !== false ) ) {
 
-			wfDebug( __METHOD__ . ": recognized $file as application/x-php\n" );
-			return "application/x-php";
+		    /* Initial checks can easily lead to false positives, since they're only
+		     * checking for a three character string in any text or binary file
+		     * Exclude files that contain 3 nulls in a row (which is present in most
+		     * binary files, but not present in text files)
+		     */
+			if ( strpos( $head, "\x00\x00\x00" ) === false ) {
+				wfDebug( __METHOD__ . ": recognized $file as application/x-php\n" );
+				return 'application/x-php';
+			}
+			else {
+				wfDebug( __METHOD__ . ": false identification of $file as application/x-php\n" );
+				$phpmatch = 'application/x-php';
+			}
 		}
 
 		/*
@@ -496,7 +508,9 @@
 		$xml = new XmlTypeCheck( $file );
 		if( $xml->wellFormed ) {
 			global $wgXMLMimeTypes;
-			if( isset( $wgXMLMimeTypes[$xml->getRootElement()] ) ) {
+			if ( $phpmatch ) {
+				return $phpmatch;
+			} elseif ( isset( $wgXMLMimeTypes[$xml->getRootElement()] ) ) {
 				return $wgXMLMimeTypes[$xml->getRootElement()];
 			} else {
 				return 'application/xml';
@@ -537,7 +551,12 @@
 			$match = array();
 
 			if ( preg_match( '%/?([^\s]+/)(\w+)%', $head, $match ) ) {
-				$mime = "application/x-{$match[2]}";
+				if ( $phpmatch ) {
+					$mime = $phpmatch;
+				}
+				else {
+					$mime = "application/x-{$match[2]}";
+				}
 				wfDebug( __METHOD__.": shell script recognized as $mime\n" );
 				return $mime;
 			}
@@ -566,6 +585,10 @@
 			return 'image/vnd.djvu';
 		}
 
+		if ( $phpmatch ) {
+			wfDebug( __METHOD__.": failed to detect other type for file $file, default to $phpmatch\n" );
+			return $phpmatch;
+		}
 		return false;
 	}