A property set in a target before CallTarget isn't set at the called target

Example:

``` XML

defined

```

```
d:\work>msbuild calltarget-property-setting.proj
Microsoft (R) Build Engine version 14.0.25420.1
Copyright (C) Microsoft Corporation. All rights reserved.

Build started 9/8/2016 4:38:12 PM.
Project "d:\work\calltarget-property-setting.proj" on node 1 (default targets).
Echo:
Property Prop:
Done Building Project "d:\work\calltarget-property-setting.proj" (default targets).

Build succeeded.
0 Warning(s)
0 Error(s)

Time Elapsed 00:00:00.02
```

That's surprising! It certainly _seems_ to have been set correctly (and a diag log indicates that too), but it's not available in the other target.

This was pointed out by @rohit21agrawal over IM.