ci: ignore rubygems warning in the "Documentation" job

A recent update in the Linux VM images used by Azure Pipelines surfaced
a new problem in the "Documentation" job. Apparently, this warning
appears 396 times on `stderr` when running `make doc`:

/usr/lib/ruby/vendor_ruby/rubygems/defaults/operating_system.rb:10: warning: constant Gem::ConfigMap is deprecated

This problem was already reported to the `rubygems` project via
https://github.com/rubygems/rubygems/issues/3068.

As there is nothing Git can do about this warning, and as the
"Documentation" job reports this warning as a failure, let's just
silence it and move on.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Acked-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/ci/test-documentation.sh b/ci/test-documentation.sh
index b3e76ef8634820646f2e2fc4b4e9b5cc2d4b97ce..de41888430a260630650341371f9fa6216a4bcbe 100755 (executable)
--- a/ci/test-documentation.sh
+++ b/ci/test-documentation.sh
@@ -7,6 +7,7 @@
 
 filter_log () {
        sed -e '/^GIT_VERSION = /d' \
+           -e "/constant Gem::ConfigMap is deprecated/d" \
            -e '/^    \* new asciidoc flags$/d' \
            -e '/stripped namespace before processing/d' \
            -e '/Attributed.*IDs for element/d' \