Update .gitignore to track cobra subdirectory

[rhcarvalho]

The 'cobra' entry on .gitignore was meant to ignore a potential 'cobra'
executable generated by 'go build' during development. However, 'cobra'
is a directory containing the command line tool, and such a generic
entry in .gitignore ignores too much.

Instead of the generic 'cobra' entry, ignore only a specific
'/cobra/cobra' path.

[CLAassistant]

All committers have signed the CLA.

[umarcor]

Hi @rhcarvalho! I just sumitted a similar PR (#946). The difference is that you ignore an explicit location cobra/cobra, while I suggest to ignore any cobra which is not cobra/. wdyt?

[rhcarvalho]

Hi @umarcor. I had considered initially a similar approach as what you wrote in your PR. However, on second thought and seeing how that line was introduced, I realized that ignoring /cobra/cobra is simpler and clearer, does what it needs to do and nothing more.

It is not possible to have a "cobra" executable in the top-level (because of the directory with the same name), and there is no good reason to generically ignore other files or directories named "cobra" in other paths.

[umarcor]

Thanks for clarifying! I'm closing #946 in favour of this.

[jharshman]

closed by #976

[umarcor]

@jharshman, #976 seems to work around this issue, but not fix it. Using the makefiles will not produce cobra/cobra. However, users that build cobra explicitly will still find it, isn't it?