Android testbed logs have excessive newlines

[mhsmith]

Bug report

Bug description:

The Android testbed can't distinguish between stdout/stderr messages which were triggered by a newline, and those triggered by a manual call to flush. This doesn't affect Python's own test suite very much, but when the testbed is used by cibuildwheel, it makes a mess of some packages' test suites. For example, pytest's "one dot per test" progress indicator shows every dot on a separate line.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Other

Linked PRs

• gh-144415: Android testbed fixes #142912
• [3.14] gh-144415: Android testbed fixes (GH-142912) #144416
• [3.13] gh-144415: Android testbed fixes (GH-142912) #144417