Regression: HTTP server would fail to serve files with binary encoding after Dan's io.encodings.iana changes from earlier today

basis/http/server/server-tests.factor

@@ -1,6 +1,21 @@
-USING: http http.server math sequences continuations tools.test ;
+USING: http http.server math sequences continuations tools.test
+io.encodings.utf8 io.encodings.binary accessors ;
 IN: http.server.tests
 
 [ t ] [ [ \ + first ] [ <500> ] recover response? ] unit-test
 
 \ make-http-error must-infer
+
+[ "text/plain; charset=UTF-8" ] [
+    <response>
+        "text/plain" >>content-type
+        utf8 >>content-charset
+    unparse-content-type
+] unit-test
+
+[ "text/xml" ] [
+    <response>
+        "text/xml" >>content-type
+        binary >>content-charset
+    unparse-content-type
+] unit-test

basis/http/server/server.factor

@@ -97,10 +97,8 @@ GENERIC: write-full-response ( request response -- )
     tri ;
 
 : unparse-content-type ( request -- content-type )
-    [ content-type>> "application/octet-stream" or ]
-    [ content-charset>> encoding>name ]
-    bi
-    [ "; charset=" glue ] when* ;
+    [ content-type>> "application/octet-stream" or ] [ content-charset>> ] bi
+    dup binary eq? [ drop ] [ encoding>name "; charset=" glue ] if ;
 
 : ensure-domain ( cookie -- cookie )
     [