On Windows, the subprocess running the sso helper does not
complete the `read()` in time. This CL reads the output
line by line, and stops reading once the required fields
have been specified.
Bug: b/360206460
Change-Id: Ib5f95093cd6f9bbbe5093a7e16393ecd97934cf2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5992110
Reviewed-by: Yiwei Zhang <yiwzhang@google.com>
Commit-Queue: Anne Redulla <aredulla@google.com>