This fix tries to address the issue raised in 24392 where
labels with duplicate keys exist in `docker info`, which
contradicts with the specifications in the docs.
The reason for duplicate keys is that labels are stored as
slice of strings in the format of `A=B` (and the input/output).
This fix tries to address this issue by checking conflict
labels when daemon started, and remove duplicate labels (K-V).
The existing `/info` API has not been changed.
An additional integration test has been added to cover the
changes in this fix.
This fix fixes 24392.
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
Upstream-commit: 7765e48aaa
Component: cli
5b01128cd3