title: git fatal: error in object: unshallow <SHA-1>
body: <p>I'm trying to unshallow a repository:</p>
  <pre><code>% /bin/git clone --shallow-since='3 years' 'https://github.com/RobertAudi/zsh-hooks'
  Cloning into 'zsh-hooks'...
  remote: Enumerating objects: 17, done.
  remote: Counting objects: 100% (17/17), done.
  remote: Compressing objects: 100% (13/13), done.
  remote: Total 17 (delta 6), reused 12 (delta 4), pack-reused 0
  Unpacking objects: 100% (17/17), 5.29 KiB | 1.76 MiB/s, done.
  % cd zsh-hooks &amp;&amp; git remote -v
  origin  https://github.com/RobertAudi/zsh-hooks (fetch)
  origin  ssh://github.com/RobertAudi/zsh-hooks (push)
  % git fetch --unshallow origin
  fatal: error in object: unshallow 9301f4e3a16df8e7cf8f37b5b93a7b925d8c8bee
  fatal: the remote end hung up unexpectedly
  </code></pre>
  <p>I have also tried changing the origin's <code>https</code> to <code>git</code> and <code>ssh</code>, but no joy.</p>
  <p>Setting:</p>
  <pre><code>git config http.postBuffer 524288000
  </code></pre>
  <p>Had no effect.</p>
  <p>I only have 5 commits in my local repo, and trying to increase the depth also failed:</p>
  <pre><code>% git fetch --depth=10
  fatal: error in object: unshallow 9301f4e3a16df8e7cf8f37b5b93a7b925d8c8bee
  </code></pre>
  <p>Further debug info:</p>
  <pre><code>% GIT_TRACE_PACKET=1 GIT_TRACE=1 GIT_CURL_VERBOSE=1 /bin/git fetch --depth=10
  12:35:07.106657 git.c:444               trace: built-in: git fetch --depth=10
  12:35:07.212298 pkt-line.c:80           packet:        fetch&gt; git-upload-pack /RobertAudi/zsh-hooks\0host=github.com\0
  12:35:07.802015 pkt-line.c:80           packet:        fetch&lt; 2a9f56433c86b332df367f6a350026e1e91035a6 HEAD\0multi_ack thin-pack side-band side-band-64k ofs-delta shallow deepen-since deepen-not deepen-relative no-progress include-tag multi_ack_detailed allow-tip-sha1-in-want allow-reachable-sha1-in-want symref=HEAD:refs/heads/master filter agent=git/github-g8735eb3c5505
  12:35:07.803152 pkt-line.c:80           packet:        fetch&lt; 75e97419cf96200cfcc4c186611f645158385dd2 refs/heads/installation-instructions
  12:35:07.803162 pkt-line.c:80           packet:        fetch&lt; 2a9f56433c86b332df367f6a350026e1e91035a6 refs/heads/master
  12:35:07.803166 pkt-line.c:80           packet:        fetch&lt; 0000
  12:35:07.811717 pkt-line.c:80           packet:        fetch&gt; want 2a9f56433c86b332df367f6a350026e1e91035a6 multi_ack_detailed side-band-64k thin-pack include-tag ofs-delta deepen-since deepen-not agent=git/2.28.0
  12:35:07.811740 pkt-line.c:80           packet:        fetch&gt; shallow 9301f4e3a16df8e7cf8f37b5b93a7b925d8c8bee
  12:35:07.811747 pkt-line.c:80           packet:        fetch&gt; shallow f59eed49cafc1b986a593a153714d3896c194a65
  12:35:07.811753 pkt-line.c:80           packet:        fetch&gt; deepen 10
  12:35:07.811758 pkt-line.c:80           packet:        fetch&gt; 0000
  12:35:08.108127 pkt-line.c:80           packet:        fetch&lt; shallow c047fc14746739e9f52cd20a71fc60cf31f63a42
  12:35:08.108208 pkt-line.c:80           packet:        fetch&lt; unshallow 9301f4e3a16df8e7cf8f37b5b93a7b925d8c8bee
  fatal: error in object: unshallow 9301f4e3a16df8e7cf8f37b5b93a7b925d8c8bee
  </code></pre>
  <p>I'm using:</p>
  <pre><code>% /bin/git --version
  git version 2.28.0
  </code></pre>