It looks like the CI builds on the master branch have been failing ever since commit
Though from looking at the contents of the commit it isn't clear why the changes would cause the build to fail.
Additionally the PR had clean CI builds, so it is also unclear why it built fine in a local branch, but then failed once merged to master.
It looks like the CI builds are also failing on the maint-64 branch as well, so this would appear to be due to something external to ICU changing.
I suspect that maybe the MSYS2 package or the VSTS Azure Image that the CI build uses might have been updated, which is now failing.
It's probably good to figure out why ICU is not building in the updated MSYS2 package.
This is likely the line that is failing:
Yeah. I was looking in about the same place. It seems like a really hacky way to figure out the current working directory. Maybe MSYS changed their shell prompt, and our little regex thing doesn't work anymore.