Upgrade mirror to Run for multiple branches (Release and Master branches)

[ahsonkhan]

We have noticed there are several commits missing in the coreclr release/2.1 branch that exists in corefx release/2.1 branch.

This means the mirror is not running on the release/2.1 branch and only runs on master.

This could lead to unexpected bugs in the product. For example, this PR just got opened for master, but corefx/2.1 and coreclr/2.1 are out of sync: dotnet/coreclr#17709

cc @weshaggard, @RussKeldorph, @joshfree, @Anipik, @safern

[safern]

The mirror's code will need to be updated to be able to specify branches we want to mirror across repos and then the mirror will have to listen to all branches that it has in the settings file to update them if needed. Shouldn't be hard, but it is still a code change. Currently I don't have bandwidth to do it, but maybe @Anipik could do it.

[safern]

cc: @danmosemsft

[Anipik]

@safern @danmosemsft I can take a look at the mirror code to do that

[ahsonkhan]

@danmosemsft ran the mirror manually for the 2.1 branches: dotnet/corefx#29256 / dotnet/coreclr#17713

Changing to blocking-release rather than blocking-RC1.

[Petermarcu]

@ahsonkhan @Anipik whats the status here? We are running out of time in 2.1.

[Anipik]

@Petermarcu The changes are in testing phase.
During my last conversation with @danmosemsft we were not sure if we want to start running the new mirror for 2.1

[Petermarcu]

Are we out of sync or are we fine for 2.1? @danmosemsft

[danmoseley]

We should be manually syncing for 2.1 release. This is essentially only relevant to Span and Path. @Anipik please manually diff and confirm they are in sync.

[Anipik]

@danmosemsft they are not in sync.
dotnet/coreclr@df62491 is missing from the corefx. Rest all is good. should i add it manually ?

[stephentoub]

dotnet/coreclr@df62491 is missing from the corefx

dotnet/corefx#29611 shouldn't have any impact, as it's mirrored as part of the common folder but it's not built into anything in corefx, e.g.

d:\repos\corefx\src>findstr /s /c:"Number.Parsing.cs" *.csproj

d:\repos\corefx\src>

[danmoseley]

Even though it's not built I suggest sending mail to shiproom @Anipik with the usual template so we can get the ok to merge this as theres value in a consistent state.
@Anipik please check the diff each day from now until we ship or you have the mirror working.

[Petermarcu]

Can we close this one now? We did the manual merge?

[Anipik]

shouldnt we just move the milestone to the future as we are currently working to run the mirror for multiple branches ?

[Petermarcu]

That would be fine too. We'd have to change the title as well then and remove the "blocking-release" tag. My goal is to get it off the radar of things blocking 2.1.