[Python] StreamReader.schema returns None

[asfimport]

Should also check this for FileWriter

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

_{Note: This issue was originally created as ARROW-595. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
PR: #434

[asfimport]

Uwe Korn / @xhochy:
Issue resolved by pull request 434
#434