Ensure that the become password is written on py3 in the ssh connection plugin

[sivel]

SUMMARY

Ensure that the become password is written on py3 in the ssh connection plugin. Fixes #34727

In python3, when subprocess.Popen is called, stdin is returned as a io.BufferedWriter.

Per the python docs for io.BufferedWriter:

The buffer will be written out to the underlying RawIOBase object under various conditions, including:

• when the buffer gets too small for all pending data;
• when flush() is called;
• when a seek() is requested (for BufferedRandom objects);
• when the BufferedWriter object is closed or destroyed.

As such we have no guarantee that the write ever happens, short of calling flush. This is specifically noticeable with pipelining enabled.

ISSUE TYPE

• Bugfix Pull Request

COMPONENT NAME

lib/ansible/plugins/connection/ssh.py

ANSIBLE VERSION

2.3
2.4
2.5

ADDITIONAL INFORMATION

[abadger]

+1 to merge and backport.

[abadger]

merged to devel and cherrypicked for 2.4.3rc3 and to the stable-2.3 tree (no new releases of 2.3.x are planned at this time but the change will be in there if we do make a new 2.3.x release in the future.)

[abadger]

After some discussion, the bug that was prompting an rc3 release has proven to change behaviour in undesirable ways so it has been reverted. Since there's (at present) no bug that's blocking 2.4.3, there may not be an rc3 and this may not make it into a release until 2.4.4.

[abadger]

Decided that we are going to treat the recursion bug as a blocker so there will be an rc3 on Wednesday next week. Cherrypicked this to stable-2.4 for the 2.4-rc3 release.