[MacPorts] #63253: py39-grpcio and py38-grpcio fail to build

[MacPorts]

#63253: py39-grpcio and py38-grpcio fail to build
------------------------+-------------------------
 Reporter:  mouse07410  |      Owner:  (none)
     Type:  defect      |     Status:  new
 Priority:  Normal      |  Milestone:
Component:  ports       |    Version:
 Keywords:              |       Port:  py39-grpcio
------------------------+-------------------------
 Big Sur 11.4, Xcode-12.5.1, everything current.

 {{{
 $ sudo port install py39-grpcio
 --->  Computing dependencies for py39-grpcio
 --->  Fetching archive for py39-grpcio
 --->  Attempting to fetch py39-grpcio-1.38.1_0.darwin_20.x86_64.tbz2 from
 https://packages.macports.org/py39-grpcio
 --->  Attempting to fetch py39-grpcio-1.38.1_0.darwin_20.x86_64.tbz2 from
 https://nue.de.packages.macports.org/py39-grpcio
 --->  Attempting to fetch py39-grpcio-1.38.1_0.darwin_20.x86_64.tbz2 from
 http://atl.us.packages.macports.org/py39-grpcio
 --->  Fetching distfiles for py39-grpcio
 --->  Verifying checksums for py39-grpcio
 --->  Extracting py39-grpcio
 --->  Configuring py39-grpcio
 --->  Building py39-grpcio
 Error: Failed to build py39-grpcio: command execution failed
 Error: See
 /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_devel_grpc/py39-grpcio/main.log
 for details.
 Error: Follow https://guide.macports.org/#project.tickets if you believe
 there is a bug.
 }}}

 Same happens with {{{py38-grpcio}}} port.

 Log attached.

-- 
Ticket URL: <https://trac.macports.org/ticket/63253>
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