As a reminder: latest clingy removed the requirement of having custom context (which made the usage of context.WithValue harder) and uses simple context instead.
Clingy saves the stdin/stdout/stderr to the context (earlier to separated context type) to make it available for unit testing.
Change-Id: I8896574f4670721de43a577cd4b35952e3b5d00e
If the cp command is executed with higher level of parallelism, it would
open more connections to storage nodes at the same time. Therefore, the
connection pool capacity should be expanded accordingly.
The pool capacity is set to 100 * parallelism.
Change-Id: Ia8b3ab6a99340d8cbb87a7b80c3354b2b21c1958