Resuming a read only file fails because its prematurely set read-only

[Gwyn Ciesla]

​https://bugzilla.redhat.com/show_bug.cgi?id=1734907

Description of problem:
Interrupted downloading of read-only files fails to resume because incomplete local file is not writeable (read-only)

Version-Release number of selected component (if applicable):
3.4.0

How reproducible:
100%

Steps to Reproduce:

1. Download read only file.
2. Cancel/stop processing queue
3. Re-download with resume

Actual results:
Partial file has remote file access mode
local: unable to open X, read-only

Expected results:

• Local partial file has current user/group and default r/w permissions
• Download continues
• When download is actually completes, user/group and access mode is matched to file on remote server