Travis-ci setup.

.travis.yml

@@ -20,7 +20,9 @@ env:
     # Supply more than one RACKET_VERSION (as in the example below) to
     # create a Travis-CI build matrix to test against multiple Racket
     # versions.
-    - RACKET_VERSION=6.0
+    #
+    # This package requires version 6.1 or later.
+    #- RACKET_VERSION=6.0
     - RACKET_VERSION=6.1
     - RACKET_VERSION=6.1.1
     - RACKET_VERSION=6.2
@@ -29,8 +31,10 @@ env:
 
 matrix:
   allow_failures:
-    env: RACKET_VERSION=HEAD
-    fast_finish: true
+    # The `debug` package used just for the tests does not work on 6.1 and 6.1.1
+    - env: RACKET_VERSION=6.1
+    - env: RACKET_VERSION=6.1.1
+  fast_finish: true
 
 before_install:
 - git clone https://github.com/greghendershott/travis-racket.git