D3716: ui: add an uninterruptable context manager that can block SIGINT

Fri Jul 27 14:23:02 EDT 2018

mharbison72 added a comment.

  Do we need a different strategy for Windows, or just eat the error?  (See the unsupported signal message)

  https://buildbot.mercurial-scm.org/builders/Win7%20x86_64%20hg%20tests/builds/808/steps/run-tests.py%20%28python%202.7.13%29/logs/stdio

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D3716

To: durin42, #hg-reviewers, indygreg
Cc: mharbison72, spectral, indygreg, yuja, martinvonz, mercurial-devel