sage-list-packages should ignore files in build/pkgs/

[jkeitel]

At the moment, sage-list-packages does not ignore files in build/pkgs, which can lead to errors if, say, your browser has automatically created a file after viewing this folder:

jkeitel@pcl337b:~/sage/sage_optional> ./sage -optional
Traceback (most recent call last):
  File "/home/pcl337b/jkeitel/sage/sage_optional/src/bin/sage-list-packages", line 57, in <module>
    with open(os.path.join(SAGE_PKGS, p, "package-version.txt")) as f:
IOError: [Errno 20] Not a directory: '/home/pcl337b/jkeitel/sage/sage_optional/build/pkgs/.directory/package-version.txt'

I am attaching a simple patch that ignores files and only checks folders.

[jdemeyer]

Replying to jkeitel:

At the moment, sage-list-packages does not ignore files in build/pkgs, which can lead to errors if, say, your browser has automatically created a file after viewing this folder

I think a better solution would be to ignore hidden files/directories. An ordinary file in build/pkgs usually does indicate a problem for which an error is appropriate.

[vbraun]

A file there isn't really indicative of an error, the packages are the subdirectories. We probably shouldn't put any files in build/pkgs but enforcing that because otherwise scripts break in an obscure way isn't good either.

[jdemeyer]

Between the following 2 options:

(a) ignore all non-directories.

(b) ignore all hidden files and directories.

I'm sure that (b) is the better option, but at this point I don't care enough to create a follow-up ticket.

[vbraun]

I'm also fine with b) but don't care so much about it that I would patch it ;-)

PS: The perfect is the enemy of the good