Update .travis.yml

pitfall/.travis.yml

@@ -9,12 +9,14 @@ env:
   global:
     - RACKET_DIR=~/racket
   matrix:
-    - RACKET_VERSION=6.12
-    - RACKET_VERSION=7.0
+    # natipkg builds for 6.12 and 7.0 have ssl but (see https://github.com/racket/racket/issues/2184)
+    #- RACKET_VERSION=6.12
+    #- RACKET_VERSION=7.0
     - RACKET_VERSION=7.1
     - RACKET_VERSION=7.2
-    - RACKET_VERSION=HEAD
-    - RACKET_VERSION=HEADCS
+    # natipkg builds not available for HEAD or HEADCS
+    #- RACKET_VERSION=HEAD
+    #- RACKET_VERSION=HEADCS
 
 # You may want to test against certain versions of Racket, without
 # having them count against the overall success/failure.