Merge pull request #1054 from pre-commit/rust_ap_linux

Fixes for rust tests on azure pipelines linux

azure-pipelines.yml

@@ -20,7 +20,7 @@ jobs:
     os: windows
     additional_variables:
       COVERAGE_IGNORE_WINDOWS: '# pragma: windows no cover'
-      TOX_TESTENV_PASSENV: COVERAGE_IGNORE_WINDOWS RUSTUP_HOME
+      TOX_TESTENV_PASSENV: COVERAGE_IGNORE_WINDOWS
       TEMP: C:\Temp  # remove when dropping python2
 - template: job--python-tox.yml@asottile
   parameters:
@@ -30,7 +30,6 @@ jobs:
     pre_test:
     - task: UseRubyVersion@0
     - template: step--git-install.yml
-    - template: step--rust-install.yml
     - bash: |
         testing/get-swift.sh
         echo '##vso[task.prependpath]/tmp/swift/usr/bin'
@@ -41,7 +40,6 @@ jobs:
     os: linux
     pre_test:
     - task: UseRubyVersion@0
-    - template: step--rust-install.yml
     - bash: |
         testing/get-swift.sh
         echo '##vso[task.prependpath]/tmp/swift/usr/bin'

tox.ini

@@ -3,7 +3,7 @@ envlist = py27,py36,py37,pypy,pypy3,pre-commit
 
 [testenv]
 deps = -rrequirements-dev.txt
-passenv = HOME LOCALAPPDATA
+passenv = HOME LOCALAPPDATA RUSTUP_HOME
 commands =
     coverage erase
     coverage run -m pytest {posargs:tests}