Auto merge of #5307 - alexcrichton:another-fix, r=matklad

Fix another issue of poisoning too eagerly

This commit extends the fix in #5288 by moving the logic added farther up in the
loop over package dependencies. This means that we won't recursively look at
optional/dev path dependencies which aren't members of the workspace. This
should fix the new issue that came up in #5257

Closes #5257