try to more reliably run the Travis PR path

.travis.yml

@@ -1,3 +1,5 @@
+language: c
+
 matrix:
   include:
     - name: "MacOS + Clang"
@@ -7,10 +9,11 @@ matrix:
       before_install:
         - pip3 install -r requirements.txt
       before_script:
+        - export COMMIT=$(git rev-parse HEAD)
         - git config --replace-all remote.origin.fetch +refs/heads/*:refs/remotes/origin/*
         - git fetch --unshallow
         - git checkout $TRAVIS_BRANCH
-        - git reset --hard $TRAVIS_COMMIT
+        - git reset --hard $COMMIT
       script:
         # Use travis-wait to allow slower tests to run
         - "cd test && travis_wait 60 python3 -m nose --rednose --verbose"
@@ -34,10 +37,11 @@ matrix:
         PQCLEAN_ONLY_DIFF: 1
         PQCLEAN_SKIP_SCHEMES: sphincs-haraka-128f-robust,sphincs-haraka-192s-robust,sphincs-sha256-128f-robust,sphincs-sha256-192s-robust,sphincs-shake256-128f-robust,sphincs-shake256-192s-robust,sphincs-haraka-128f-simple,sphincs-haraka-192s-simple,sphincs-sha256-128f-simple,sphincs-sha256-192s-simple,sphincs-shake256-128f-simple,sphincs-shake256-192s-simple,sphincs-haraka-128s-robust,sphincs-haraka-256f-robust,sphincs-sha256-128s-robust,sphincs-sha256-256f-robust,sphincs-shake256-128s-robust,sphincs-shake256-256f-robust,sphincs-haraka-128s-simple,sphincs-haraka-256f-simple,sphincs-sha256-128s-simple,sphincs-sha256-256f-simple,sphincs-shake256-128s-simple,sphincs-shake256-256f-simple,sphincs-haraka-192f-robust,sphincs-haraka-256s-robust,sphincs-sha256-192f-robust,sphincs-sha256-256s-robust,sphincs-shake256-192f-robust,sphincs-shake256-256s-robust,sphincs-haraka-192f-simple,sphincs-haraka-256s-simple,sphincs-sha256-192f-simple,sphincs-sha256-256s-simple,sphincs-shake256-192f-simple,sphincs-shake256-256s-simple
       before_install:
+        - export COMMIT=$(git rev-parse HEAD)
         - git config --replace-all remote.origin.fetch +refs/heads/*:refs/remotes/origin/*
         - git fetch --unshallow
         - git checkout $TRAVIS_BRANCH
-        - git reset --hard $TRAVIS_COMMIT
+        - git reset --hard $COMMIT
         - pip3 install -r requirements.txt
         - brew link gcc
         - export PATH="/usr/local/bin:$PATH"