Travis: Workaround travis-ci/travis-ci#8552

Author: leezer3

.travis.yml

@@ -9,7 +9,7 @@ matrix:
       script: make publish
     - os: osx
       mono: latest
-      before_install: brew install hudochenkov/sshpass/sshpass
+      before_install: if [ "$TRAVIS_OS_NAME" == "osx" ]; then brew update; brew install hudochenkov/sshpass/sshpass; fi
       script: make publish
 
 #Test builds
@@ -20,7 +20,7 @@ matrix:
       script: make all-release
     - os: osx
       mono: latest
-      before_install: brew install hudochenkov/sshpass/sshpass
+      before_install: if [ "$TRAVIS_OS_NAME" == "osx" ]; then brew update; brew install hudochenkov/sshpass/sshpass; fi;
       script: make all-release
     - os: linux
       dist: precise
@@ -37,7 +37,7 @@ matrix:
       solution: OpenBVE.sln
     - os: osx
       mono: latest
-      before_install: brew install hudochenkov/sshpass/sshpass
+      before_install: if [ "$TRAVIS_OS_NAME" == "osx" ]; then brew update; brew install hudochenkov/sshpass/sshpass; fi;
       solution: OpenBVE.sln
     - os: linux
       dist: precise