missing space

travis is very picky and does not understand "allow_failure"
if there is a wrong number of spaces

.travis.yml

@@ -20,7 +20,7 @@ env:
   - PLUMED_CC=gcc   PLUMED_CXX=g++   CPPCHECK=yes
 matrix:
   allow_failures:
-    - env: PLUMED_CC=gcc   PLUMED_CXX=g++  CPPCHECK=yes
+    - env: PLUMED_CC=gcc   PLUMED_CXX=g++   CPPCHECK=yes
 # Possible additional variables:
 #   VALGRIND=yes to make valgrind tests, only when log contains string [valgrind]
 install: