Permit Windows tests on Travis to fail fast

.travis.yml

@@ -4,6 +4,7 @@ linux_before_install: &linuxbefore
   - sudo apt-get install -y libblas-dev liblapack-dev libatlas-base-dev gfortran
 
 jobs:
+  fast_finish: true
   include:
     - name:  "Python 3.6 on Xenial Linux"
       dist: xenial
@@ -31,6 +32,15 @@ jobs:
         - choco install miktex.portable
         - python -m pip install --upgrade pip
       env: PATH=/c/Python38:/c/Python38/Scripts:$PATH
+  allow_failures:
+    - name: "Python 3.8.0 on Windows"
+      os: windows           # Windows 10.0.17134 N/A Build 17134
+      language: shell       # 'language: python' is an error on Travis CI Windows
+      before_install:
+        - choco install python --version 3.8.0
+        - choco install miktex.portable
+        - python -m pip install --upgrade pip
+      env: PATH=/c/Python38:/c/Python38/Scripts:$PATH
 
 install:
   - pip3 install --editable ".[dev]"