remove use of sudo in Travis config

[dougxc]

No description provided.

[gilles-duboscq]

Interesting error in the 2.6 Travis job. from mx import DateTime is really code from optik_ext.py that is used by pylint.

[dougxc]

Rather than figure out why this is happening, I say we leave the sudo usage in.

[gilles-duboscq]

I noticed that in fact this is actually showing that we are not 2.6 compatible: on the non-sudo infrastructure we really get python 2.6 and we have syntax problems.
All the other travis builds that seem to be using 2.6 are actually running on 2.7: the mx script is picking up a 2.7 install which, while not default, is present on the sudo-enabled builders.

[dougxc]

Currently, mx is not 2.6 compatible. The few uses of multi-context-manager with statements and single use of OrderedDict can be replaced with 2.6 compatible code. However, the argparse module was only introduced in 2.7. A workaround for this is to simply place argparse.py on PYTHONPATH.
The bigger question is whether we really need to worry about 2.6 compatibility?

[mbrantner]

Oracle Linux 6.5 comes with Pyton 2.6.6. It would be great if that was supported.

[dougxc]

I can make mx parse with 2.6 fairly easy by making the changes mentioned above. However, usages of certain 2.7 features will only be caught dynamically. The biggest offender I know of is "Changed in version 2.7: The positional argument specifiers can be omitted, # so '{} {}' is equivalent to '{0} {1}'.".

[gilles-duboscq]

The {} can easily be grepped.
In any case, we should either make it 2.6 compatible or stop testing using 2.6.
Regarding argparse, that would be an other advantage of being a python package with a setup.py: we could just require argparse as a dependency.
One problem there is that there is already a python package called mxon pypi...

[dougxc]

Grepping for the pattern "[^"\n]+\{\} shows 39 hits and "[^"\n]+\{\} shows 106 hits in the mx related Python files I have open in Eclipse. These will have to be converted. Unfortunately, I can't see a pylint check to prevent them creeping back in.

[dougxc]

I've further investigated the work required to make mx 2.6 compatible and enforce this compatibility on all mx extensions and it's not exactly trivial due to the issue with {} in format specifiers mentioned above. One can use the ast Python module to parse for string constants containing {} but it's hard to know whether they're used as format strings. Also, there's nothing preventing a format string being non-constant. In any case, until there's a more compelling reason to support 2.6, I'm going to disable 2.6 testing.