get mingw32 to work, enable pytest fast-fail

build.py

@@ -65,7 +65,7 @@ elif install_mode == 'test':
         os.chdir('tmp')
 
         x('python -m spacy.en.download')
-        x('python -m pytest ../spacy/ --models --vectors --slow')
+        x('python -m pytest ../spacy/ -x --models --vectors --slow')
 
     finally:
         os.chdir(old)

venv.ps1

@@ -9,7 +9,15 @@ $ErrorActionPreference = "Stop"
 
 if(!(Test-Path -Path ".build"))
 {
+    if($compiler -eq "mingw32")
+    {
         virtualenv .build --system-site-packages --python $python
+    }
+    else
+    {
+        virtualenv .build --python $python
+    }
+
     if($compiler)
     {
         "[build]`r`ncompiler=$compiler" | Out-File -Encoding ascii .\.build\Lib\distutils\distutils.cfg