ResolveRevision doesn't resolve on abbreviated unique hashes

As per the gitrevisions documentation (https://mirrors.edge.kernel.org/pub/software/scm/git/docs/gitrevisions.html), abbreviated SHA "leading substring that is unique within the repository" should be resolved:

<sha1>, e.g. dae86e1950b1277e545cee180551750029cfe735, dae86e The full SHA-1 object name (40-byte hexadecimal string), or a leading substring that is unique within the repository. E.g. dae86e1950b1277e545cee180551750029cfe735 and dae86e both name the same commit object if there is no other object in your repository whose object name starts with dae86e.

However, ResolveRevision() in go-git will error if given a rev string which is not the full 40 characters.

Quick sample code to run within a repo:

package main

import (
    "fmt"

    "gopkg.in/src-d/go-git.v4"
    "gopkg.in/src-d/go-git.v4/plumbing"
)

func main() {
    r, _ := git.PlainOpen(".")
    head, _ := r.Head()
    hashString := head.Hash().String()
    shortHash := hashString[:8]

    logAttemptedResolve(r, plumbing.Revision(hashString))
    logAttemptedResolve(r, plumbing.Revision(shortHash))
}

func logAttemptedResolve(r *git.Repository, rev plumbing.Revision) {
    hash, err := r.ResolveRevision(rev)
    fmt.Printf(`
attempted to resolve %v
    got: %v
    error: %v
`, rev, hash, err)
}

Produces:

attempted to resolve 2c46957dd2fdd7daf8502a27b4e7c0bfbfb15e51
    got: 2c46957dd2fdd7daf8502a27b4e7c0bfbfb15e51
    error: <nil>

attempted to resolve 2c46957d
    got: 0000000000000000000000000000000000000000
    error: reference not found

src-d / go-git

ResolveRevision doesn't resolve on abbreviated unique hashes #1148