demandimport: add 'brotli' to ignores, so urllib3 can detect its absence

Pushing to GitHub fails under Python 2.7 without this.

#326
18 jobs for branch/default in 3 minutes and 22 seconds
Status Job ID Name Coverage
  Current
passed #124110
tests-py2-hg-5.4

00:01:08

passed #124111
tests-py3-hg-5.4

00:00:47

 
  Compat
passed #124124
tests-py2-hg-4.3

00:01:05

passed #124123
tests-py2-hg-4.4

00:00:43

passed #124122
tests-py2-hg-4.5

00:01:08

passed #124121
tests-py2-hg-4.6

00:01:03

passed #124120
tests-py2-hg-4.7

00:01:06

passed #124119
tests-py2-hg-4.8

00:01:16

passed #124118
tests-py2-hg-4.9

00:01:15

passed #124117
tests-py2-hg-5.0

00:01:12

passed #124116
tests-py2-hg-5.1

00:01:14

passed #124115
tests-py2-hg-5.2

00:01:09

passed #124114
tests-py2-hg-5.3

00:01:10

failed #124112
allowed to fail
tests-py2-hg-default

00:02:08

passed #124113
tests-py2-hg-stable

00:02:14

passed #124127
tests-py3-hg-5.3

00:00:26

passed #124125
tests-py3-hg-default

00:01:01

passed #124126
tests-py3-hg-stable

00:01:11

 
Name Stage Failure
failed
tests-py2-hg-default Compat
Failed test-timezone.t: output changed
Failed test-tree-decomposition.t: output changed and returned error code 1
Failed test-verify-fail.t: output changed
# Ran 40 tests, 1 skipped, 37 failed.
python hash seed: 1191879254
# Cleaning up HGTMP /tmp/hgtests.Csn4zr
Running after_script
Uploading artifacts for failed job
ERROR: Job failed: exit code 1