CI: Use conda for 3.8 build (#29696)

Author: TomAugspurger

.travis.yml

@@ -30,11 +30,9 @@ matrix:
       - python: 3.5
 
     include:
-    - dist: bionic
-      # 18.04
-      python: 3.8.0
+    - dist: trusty
       env:
-        - JOB="3.8-dev" PATTERN="(not slow and not network)"
+        - JOB="3.8" ENV_FILE="ci/deps/travis-38.yaml" PATTERN="(not slow and not network)"
 
     - dist: trusty
       env:
@@ -88,7 +86,7 @@ install:
 script:
   - echo "script start"
   - echo "$JOB"
-  - if [ "$JOB" != "3.8-dev" ]; then source activate pandas-dev; fi
+  - source activate pandas-dev
   - ci/run_tests.sh
 
 after_script:

ci/build38.sh

@@ -0,0 +1,16 @@
+name: pandas-dev
+channels:
+  - defaults
+  - conda-forge
+dependencies:
+  - python=3.8.*
+  - cython>=0.29.13
+  - numpy
+  - python-dateutil
+  - nomkl
+  - pytz
+  # universal
+  - pytest>=5.0.0
+  - pytest-xdist>=1.29.0
+  - hypothesis>=3.58.0
+  - pip

ci/deps/travis-38.yaml

@@ -1,10 +1,5 @@
 #!/bin/bash -e
 
-if [ "$JOB" == "3.8-dev" ]; then
-    /bin/bash ci/build38.sh
-    exit 0
-fi
-
 # edit the locale file if needed
 if [ -n "$LOCALE_OVERRIDE" ]; then
     echo "Adding locale to the first line of pandas/__init__.py"