Parse the commands in reverse order
Parse the commands in reverse order

Although the SHA can now be omitted when approving a pull request, a
command like `@homu r+ p=10` still fails because `r+` tries to parse
`p=10` as a SHA. To handle this correctly, the commands will be parsed
in reverse order.

Also, the `r+` command will ignore an argument that does not look like a
SHA.

fizzy123/homu,coupa/homu,frewsxcv/homu,barosl/homu,acmcarther/homu,acmcarther/homu,mvines/homu,coldnight/homu,mvines/homu,servo/homu,frewsxcv/homu,tempbottle/homu,barosl/homu,fizzy123/homu,servo/homu,coupa/homu,coldnight/homu,tempbottle/homu,karen-irc/homu,karen-irc/homu