ci: alias 127.0.0.2/.3 on macOS lo0 for the connect-fallback test

macOS configures only 127.0.0.1 as loopback, so 19_local-connect-fallback's
dead 127.0.0.2/.3 addresses have no fast-refuse path: the connect intermittently
stalls to the timeout and logs "Connect Time Out", which the zero-errors
assertion rejects (flaked ~1/6 on the macOS runner). #531's --timeout/--retries
bound the stall but not the spurious error. Aliasing the addresses onto lo0
makes them refuse instantly like Linux, so the fallback runs cleanly.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Xavier Roche <roche@httrack.com>

.github/workflows/ci.yml

@@ -135,6 +135,14 @@ jobs:
       - name: Build
         run: make -j"$(sysctl -n hw.ncpu)"
 
+      - name: Add loopback aliases (macOS lacks 127.0.0.2/.3)
+        # 19_local-connect-fallback needs the dead 127.0.0.2/.3 to refuse
+        # instantly like Linux; alias them onto lo0 so they don't stall to timeout.
+        run: |
+          set -euo pipefail
+          sudo ifconfig lo0 alias 127.0.0.2 up
+          sudo ifconfig lo0 alias 127.0.0.3 up
+
       - name: Test
         run: |
           jobs=$(( $(sysctl -n hw.ncpu) * 2 )); [ "$jobs" -le 16 ] || jobs=16