ci: merge the i1686-gnu images

Author: pietroalbini

.azure-pipelines/auto.yml

@@ -126,10 +126,8 @@ jobs:
 
       asmjs:
         IMAGE: asmjs
-      i686-gnu-1:
-        IMAGE: i686-gnu-1
-      i686-gnu-2:
-        IMAGE: i686-gnu-2
+      i686-gnu:
+        IMAGE: i686-gnu
       i686-gnu-nopt:
         IMAGE: i686-gnu-nopt
       test-various:

src/ci/docker/i686-gnu-2/Dockerfile

@@ -18,5 +18,10 @@ COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
 ENV RUST_CONFIGURE_ARGS --build=i686-unknown-linux-gnu
-ENV SCRIPT make ci-subset-1
-
+# Exclude some tests that are unlikely to be platform specific, to speed up
+# this slow job.
+ENV SCRIPT python2.7 ../x.py test \
+  --exclude src/bootstrap \
+  --exclude src/test/rustdoc-js \
+  --exclude src/tools/error_index_generator \
+  --exclude src/tools/linkchecker