Plots view fails with nested Git branch names

[jorgeorpinel]

Branch names with / (directories in .git/refs/heads/ ) aren't getting picked up correctly internally. I get this from a readme/known-limitations branch, for example:

OUTPUT:

[version: 0.3.6, 2022-06-24T16:24:46.910Z, pid: 10780] > dvc plots diff known-limitations workspace -o .dvc/tmp/plots --split --show-json - FAILED with code 1 (498ms)
ERROR: unknown Git revision 'known-limitations'

[mattseddon]

The bug is in dvc exp show --show-json. known-limitations is returned as the branch name:

/vscode-dvc/demo readme/known-limitations *1 !2 ❯ dvc exp show --show-json
{
  "workspace": {
    "baseline": {
      "data": {
        "timestamp": null,
        "params": {
          "params.yaml": {
            "data": {
              "lr": 0.003,
              "weight_decay": 0,
              "epochs": 15
            }
          }
        },
        "deps": {
          "data/MNIST": {
            "hash": "0aed307494600d178fbdc0d000d6db38.dir",
            "size": 66544866,
            "nfiles": 10
          },
          "train.py": {
            "hash": "90f29a92c178927514c7f4d61a984a8a",
            "size": 4865,
            "nfiles": null
          }
        },
        "outs": {
          "model.pt": {
            "hash": "c7a5760efd52d3759d8e546ab867f4a6",
            "size": 439383,
            "nfiles": null,
            "use_cache": true,
            "is_data_source": false
          },
          "data/MNIST/raw": {
            "hash": "8c257df187855c681f88bde92d721ccd.dir",
            "size": 66544770,
            "nfiles": 8,
            "use_cache": true,
            "is_data_source": true
          }
        },
        "queued": false,
        "running": false,
        "executor": null,
        "metrics": {
          "training_metrics.json": {
            "data": {
              "step": 14,
              "loss": 0.9756642580032349,
              "acc": 0.7659
            }
          }
        }
      }
    }
  },
  "4d78b9e7158ee1d6504028f79f65daf48d2d9af3": {
    "baseline": {
      "data": {
        "timestamp": "2022-06-25T05:52:02",
        "params": {
          "params.yaml": {
            "data": {
              "lr": 0.003,
              "weight_decay": 0,
              "epochs": 15
            }
          }
        },
        "deps": {
          "data/MNIST": {
            "hash": "0aed307494600d178fbdc0d000d6db38.dir",
            "size": 66544866,
            "nfiles": 10
          },
          "train.py": {
            "hash": "90f29a92c178927514c7f4d61a984a8a",
            "size": 4865,
            "nfiles": null
          }
        },
        "outs": {
          "model.pt": {
            "hash": "38126781764ca9fb04496ca2c2173056",
            "size": 439383,
            "nfiles": null,
            "use_cache": true,
            "is_data_source": false
          },
          "data/MNIST/raw": {
            "hash": "8c257df187855c681f88bde92d721ccd.dir",
            "size": 66544770,
            "nfiles": 8,
            "use_cache": true,
            "is_data_source": true
          }
        },
        "queued": false,
        "running": false,
        "executor": null,
        "metrics": {
          "training_metrics.json": {
            "data": {
              "step": 14,
              "loss": 0.9596208930015564,
              "acc": 0.7735
            }
          }
        },
        "name": "known-limitations"
      }
    }
  }
}

I checked to see if plots diff can handle being called with a revision that contains a path separator and it cannot. For now I have raised:

1. exp show: branch name containing path separator not returned for HEAD dvc#7933
2. plots diff: fails when given a revision which contains a path separator dvc#7934

[mattseddon]

I have merged a patch for this.

[jorgeorpinel]

Thanks @mattseddon. Should we close this in favor of iterative/dvc#7933 or are both still needed?