BUG #14052: outfile of pg_basebackup , are of different type. But after extractin the file size is same

The following bug has been logged on the website:

Bug reference: 14052
Logged by: Sasi Kishore K
Email address: Sasikishore(dot)k(at)gmail(dot)com
PostgreSQL version: 9.4.4
Operating system: Linux and Windows
Description:

Hello,

We are using pg_basebackup to take the database backup. The size of gz file
generated is not consistent. Few times it generating the file with double
the size of the other generated files.

But after extracting the gz file, the content is same and also file size is
same. Checked with with diff tools also almost all the files are identical
except few file name changes.

Can please let us know, what can cause to generate the backup file with
double the size of the file ?

Thanks,
Sasi