Do not complain the : comes before prepend-path (alisw#1938)

.travis.yml

@@ -20,7 +20,7 @@ script: |
     # In any case we correctly handle rpath in our macOS builds.
     grep -v "unset DYLD_LIBRARY_PATH" $X | grep DYLD_LIBRARY_PATH && ERR="$ERR $X"
     # Modules 4 does not allow having colons in prepend-path anymore
-    grep prepend-path $X | grep ':' && ERR="$ERR $X"
+    grep -e "prepend-path.*[:]" $X && ERR="$ERR $X"
     [[ $X == defaults-*.sh ]] && continue
 
     # If a recipe is not a system requirement, it must have a Modulefile