[temp] bring back all tests

.appveyor.yml

@@ -53,7 +53,7 @@ build: off
 
 environment:
   # unless indicated otherwise, we test datalad_next
-  DTS: datalad_next.patches.tests.test_patched_ria_ora
+  DTS: datalad_next
   # SSH testing is done via a side-loaded container that provides a POSIX/SSHable
   # server environment
   DATALAD_TESTS_DOCKER_SSHD_SECKEY_DOWNLOADURL: https://ci.appveyor.com/api/projects/mih/datalad-ci-docker-containers/artifacts/recipes/sshd/id_rsa?job=sshd
@@ -67,8 +67,6 @@ environment:
   DATALAD_TESTS_SERVER_SSH_PATH: /usr/local/apache2/htdocs
   DATALAD_TESTS_SERVER_LOCALPATH: /home/appveyor/DLTMP/sshdroot
 
-  DATALAD_EXTENSIONS_LOAD: next
-
   # Do not use `image` as a matrix dimension, to have fine-grained control over
   # what tests run on which platform
   # The ID variable had no impact, but sorts first in the CI run overview
@@ -133,6 +131,98 @@ environment:
       DATALAD_TESTS_SERVER_SSH_PATH: /Users/appveyor/DLTMP/riaroot
       DATALAD_TESTS_SERVER_LOCALPATH: /Users/appveyor/DLTMP/riaroot
 
+    # run a subset of the core tests on the oldest supported Python version
+    - job_name: datalad-core-1
+      DTS: >
+        datalad.cli
+        datalad.core
+      # do not run tests that ensure behavior we intentionally changed
+      # - test_gh1811: is included in next in an alternative implementation
+      # - test_librarymode: assumes that CLI config overrides end up in the
+      #   session `datalad.cfg.overrides`, but -next changes that behavior
+      #   to have `.overrides` be uniformly limited to instance overrides
+      KEYWORDS: not test_gh1811 and not test_librarymode
+      APPVEYOR_BUILD_WORKER_IMAGE: Ubuntu2004
+      PY: 3.8
+      INSTALL_SYSPKGS:
+      # datalad-annex git remote needs something after git-annex_8.20211x
+      INSTALL_GITANNEX: git-annex -m snapshot
+      CODECOV_BINARY: https://uploader.codecov.io/latest/linux/codecov
+    - job_name: datalad-core-2
+      DTS: >
+        datalad.customremotes
+        datalad.dataset
+        datalad.distributed
+        datalad.downloaders
+        datalad.interface
+      # do not run tests that ensure behavior we intentionally changed
+      # - test_gh1811: is included in next in an alternative implementation
+      # - test_fake_gitlab: we have an updated variant in next
+      # - test_dryrun: we have an updated variant in next; what is disabled is
+      #   the one in test_create_sibling_gitlab.py. However, there is one with
+      #   identical name in test_create_sibling_ghlike.py, now also disabled
+      #   because MIH does not know better
+      KEYWORDS: >
+        not test_gh1811
+        and not test_fake_gitlab
+        and not test_dryrun
+        and not test_initremote
+        and not test_push_url
+        and not test_read_access
+        and not test_ria_postclone_noannex
+        and not test_version_check_ssh
+        and not test_version_check
+        and not test_obtain_permission_ssh
+        and not test_obtain_permission_root
+        and not test_remote_layout
+        and not test_remote_layout_ssh
+        and not test_setup_store
+        and not test_setup_ds_in_store
+        and not test_initremote_basic_fileurl
+        and not test_initremote_basic_httpurl
+        and not test_initremote_basic_httpsurl
+        and not test_initremote_basic_sshurl
+        and not test_gitannex_local
+        and not test_gitannex_ssh
+        and not test_ria_postclonecfg
+      APPVEYOR_BUILD_WORKER_IMAGE: Ubuntu2004
+      PY: 3.8
+      INSTALL_SYSPKGS:
+      # datalad-annex git remote needs something after git-annex_8.20211x
+      INSTALL_GITANNEX: git-annex -m snapshot
+      CODECOV_BINARY: https://uploader.codecov.io/latest/linux/codecov
+    - job_name: datalad-core-3
+      DTS: >
+        datalad.distribution
+      KEYWORDS: not test_invalid_args
+      APPVEYOR_BUILD_WORKER_IMAGE: Ubuntu2004
+      PY: 3.8
+      INSTALL_SYSPKGS:
+      # datalad-annex git remote needs something after git-annex_8.20211x
+      INSTALL_GITANNEX: git-annex -m snapshot
+      CODECOV_BINARY: https://uploader.codecov.io/latest/linux/codecov
+    - job_name: datalad-core-4
+      DTS: >
+        datalad.local
+      APPVEYOR_BUILD_WORKER_IMAGE: Ubuntu2004
+      PY: 3.8
+      INSTALL_SYSPKGS:
+      # datalad-annex git remote needs something after git-annex_8.20211x
+      INSTALL_GITANNEX: git-annex -m snapshot
+      CODECOV_BINARY: https://uploader.codecov.io/latest/linux/codecov
+    - job_name: datalad-core-5
+      DTS: >
+        datalad.runner
+        datalad.support
+        datalad.tests
+        datalad.ui
+      APPVEYOR_BUILD_WORKER_IMAGE: Ubuntu2004
+      PY: 3.8
+      INSTALL_SYSPKGS:
+      # datalad-annex git remote needs something after git-annex_8.20211x
+      INSTALL_GITANNEX: git-annex -m snapshot
+      CODECOV_BINARY: https://uploader.codecov.io/latest/linux/codecov
+
 
 # only run the CI if there are code or tooling changes
 only_commits:
@@ -275,8 +365,6 @@ for:
       # (avoiding length-limits as much as possible)
       - cmd: "set TMP=C:\\DLTMP"
       - cmd: "set TEMP=C:\\DLTMP"
-      - cmd: "set DATALAD_EXTENSIONS_LOAD=next"
-
       # establish a root directory for SSH tests
       - cmd: "md %DATALAD_TESTS_SERVER_LOCALPATH%"