Module admin fails on uncompressed tar files

Uncompressed tarballs break Module Admin.

The source admin/libraries/modulefunctions.class.php uses tar zxf filename for .tar. .tgz, and .tar.gz files.  This makes it incapable of handling uncompressed.

Simply removing the "z" and changing the command lines to tar xf filename resolves the issue - gzipped tar files are automatically handed by all remotely recent gnu tar versions (tested back to CentOS 6).

Problem is compounded by the fact the rmccue request library will sometimes automatically de-compress  gzipped files from some servers, so "Download from Web" can break even if the source is a .tgz file.