tree b1701f02354a216cda29cc4b6d05ff7ec246d900
parent 09ef8dfc8e7b6d5b7594be417e875e4ba57bcad0
author Greg Spencer <gspencergoog@users.noreply.github.com> 1590618646 -0700
committer dart-luci-ci-builder <dart-luci-ci-builder@dart-ci.iam.gserviceaccount.com> 1590618827 -0700

Update the flutter script's locking mechanism and follow_links (#57590)

Update the flutter and dart scripts' locking mechanism and follow_links function to be more robust and support more platforms.

This adds support for using mkdir as a fallback if the system doesn't have flock instead of using shlock, since shlock doesn't work on shared filesystems.

It also fixes a problem in the follow_links function where it failed when the link resolved to the root directory.
https://dart.googlesource.com/external/github.com/flutter/flutter/+/379e11b64194bd9b1b4a159134476d69856f8d11