Travis: stable is now 0.4.0

Move stable job and update comments.

Add a TODO for 0.4.0 and 0.4.1 nightlies

Closes 30876.

.travis.yml

@@ -63,26 +63,27 @@ matrix:
             - shellcheck
             - tor
       env: TOR="0.2.9-nightly" NETWORK_FLAVOUR="basic-min"
-    ## The current stable release is 0.3.5, so we don't have a separate
-    ## 0.3.5-stable job
     - addons:
         apt:
           sources:
-            - sourceline: 'deb https://deb.torproject.org/torproject.org xenial main'
+            - sourceline: 'deb https://deb.torproject.org/torproject.org tor-nightly-0.3.5.x-xenial main'
               key_url: 'https://deb.torproject.org/torproject.org/A3C4F0F979CAA22CDBA8F512EE8CBC9E886DDD89.asc'
           packages:
             - shellcheck
             - tor
-      env: TOR="stable-release" NETWORK_FLAVOUR="basic-min"
+      env: TOR="0.3.5-nightly" NETWORK_FLAVOUR="basic-min"
+    ## The current stable release is 0.4.0
     - addons:
         apt:
           sources:
-            - sourceline: 'deb https://deb.torproject.org/torproject.org tor-nightly-0.3.5.x-xenial main'
+            - sourceline: 'deb https://deb.torproject.org/torproject.org xenial main'
               key_url: 'https://deb.torproject.org/torproject.org/A3C4F0F979CAA22CDBA8F512EE8CBC9E886DDD89.asc'
           packages:
             - shellcheck
             - tor
-      env: TOR="0.3.5-nightly" NETWORK_FLAVOUR="basic-min"
+      env: TOR="stable-release" NETWORK_FLAVOUR="basic-min"
+    ## TODO: add 0.4.0-nightly and experimental-0.4.1 when available
+    ## See #30826.
 
     ## Test all supported python releases
     ## Pre-installed in Travis xenial: