Check existence of patch(1)

[arnested]

In bandaid.drush.inc we should check whether the patch(1) command actually exists.

I just discovered a CentOS server that came without the patch command installed. The error message from Bandaid was just "Could not apply patch" (which is of course not false but I guess we could be more helpful).

[xendk]

Suggestions on how to do that?

[arnested]

Hmmm... Getting the cause of a failed patch doesn't look easy.

We could change the last part of _bandaid_attempt_patch() and print $output to the screen if patching failed. That could provide some kind of hint no matter what caused an error.