[Python] Flight tests failing on Python 2.7

[asfimport]

See build https://ci.ursalabs.org/#/builders/72/builds/1084

Reporter: Wes McKinney / @wesm
Assignee: Wes McKinney / @wesm

PRs and other links:

• GitHub Pull Request #4553

_{Note: This issue was originally created as ARROW-5596. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 4553
#4553