Actually, you are already in the committers group. Have you experienced this recently?

Yes. The "needs an L-G-T-M from a full committer" error happened to me in Rietveld on a merge I tried earlier today. (And the auto-land in drover has always failed for me with a vague error.)

Though it occurs to me that I was just assuming an LGTM isn't necessary to commit an approved merge if you are a committer yourself--is that not supposed to be the case?

Further context re: the failing to land in drover with the -v flag:

error: failed to push some refs to 'https://chromium.googlesource.com/chromium/src.git'
Failed to push. If this persists, please file a bug.
DEBUG:root:Deleting /tmp/drover_2924_iVduk9
DEBUG:root:Running git branch -D drover_2924_iVduk9 (cwd '/usr/local/google/home/tmartino/chromium/src')
Error: Command 'cl land --bypass-hooks' failed: Command '['git', 'cl', 'land', '--bypass-hooks']' returned non-zero exit status 1

Hm, then we have two problems here.

First, the missing L-G-T-M message. It'd be great to see actual CL.
This https://chrome-infra-auth.appspot.com/auth/api/v1/memberships/list?identity=user:tmartino@chromium.org says that you chromium address is a committer, so I'd need a CL to debug further. Is it possible that your CL description didn't include a TBR=some-other-committer@chromium.org line?

Second, the manual git cl land failure to push. Please, visit chromium-review.googlesource.com/new-password and follow instructions. Important: select specifically chromium.googlesource.com instead of *.googlesource.com. Then make sure your ~/.gitcookies doesn't contain *.googlesource.com OR duplicated chromium.googlesource.com lines.

Thanks, your suggestions solved both problems.