Base: port rdeps --full, infinite loop on circular dependency

[Dave-Allured (Dave Allured)]

This was first reported in port bug #62277 for py-attrs circular dependency. This is the bug report for rdeps in the base, not the port.

port rdeps --full py-attrs prints endlessly in infinite loop.
port rdeps py-attrs prints normally and shows 37 dependencies.

• Base version 2.6.4
• py-attrs @20.3.0_0
• py-hypothesis @6.8.4_0
• Mac OS 10.14.5

• py-attrs --> py-hypothesis --> py-attrs
• py-attrs is a normal library dependency of py-hypothesis.
• py-hypothesis is a test dependency of py-attrs.

Requested base behavior:

• Print warning message when circular dependency is first encountered.
• Do not recurse into circular dependency.

[jmroot (Joshua Root)]

In 49df406d8273f203d30186a77251a897f9d8ef79/macports-base (master):

rdeps --full: don't infinitely loop on circular deps

Fixes: #62711

[jmroot (Joshua Root)]

Note that the full rdeps of py-attrs are still close to 2 million lines with this fixed. Using --no-test makes it much more manageable.

[Dave-Allured (Dave Allured)]

Thanks Joshua. 2 million lines -- that is impressive. I shall be forewarned!