This fix tries to address issues related to #23221 where Dockerignore
may consists of UTF-8 BOM. This likely happens when Notepad
tries to save a file as UTF-8 in Windows.
This fix skips the UTF-8 BOM bytes from the beginning of the
Dockerignore if exists.
Additional tests has been added to cover the changes in this fix.
This fix is related to #23221 (UTF-8 BOM in Dockerfile).
Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
Upstream-commit: ea86320fcc61ea9ded3eef7ba01699c4e3ccf3ce
Component: engine
ab25cb22b0