Completions for some long options are missing. (doesn't parse --help output perfectly)

bash_completion uses
 sed -ne 's/.*\(--[-A-Za-z0-9]\{1,\}=\{0,1\}\).*/\1/p'
to parse the options out of the --help output for MANY commands, including grep.

Unfortunately, it trips up on lines like this from grep:
  -r, --recursive like --directories=recurse

because the .* matches right up to before --directories=recurse. d'oh.
It gets --directories out of that line.

fixed it:

echo ' -r, --recursive like --directories=recurse' | sed -ne 's/\([^-]\|-[^-]\)*\(--[-A-Za-z0-9]\{1,\}=\{0,1\}\).*/\2/p'
--recursive

using \([^-]\|-[^-]\)* instead of .* at the front of the pattern makes the greedy match at the front stop at the first --. If there are commands that use -- as formatting in their --help output, then this won't work, e.g.
 -r -- equivalent to --recursive
but otherwise this should be good. It's pretty much standard to list the actual options early in a line, rather than
  like --directories=recurse -r, --recursive

This goes in _longopt(), line 1801 of bash_completion.

I'll submit this upstream, too

upstream https://alioth.debian.org/tracker/index.php?func=detail&aid=314896&group_id=100114&atid=413095

Patch attached there. Also fixes
ls --directory --[TAB] => now completes options

  rather than deciding that it's right and user is wrong, and only accepting a directory name. Not smart for such a naive function.

I don't know if the patch was accepted upstream, but this hasn't made it to Ubuntu.

Test cases in OP and comment #6 still fail on Zesty.