Adds IRepository.IsSha

src/Tgstation.Server.Host/Components/Repository/IRepository.cs

@@ -45,6 +45,14 @@ namespace Tgstation.Server.Host.Components.Repository
 		/// </summary>
 		string Origin { get; }
 
+		/// <summary>
+		/// Checks if a given <paramref name="committish"/> is a sha
+		/// </summary>
+		/// <param name="committish">The git object to check</param>
+		/// <param name="cancellationToken">The <see cref="CancellationToken"/> for the operation</param>
+		/// <returns>A <see cref="Task{TResult}"/> resulting in <see langword="true"/> if <paramref name="committish"/> is a sha, <see langword="false"/> otherwise</returns>
+		Task<bool> IsSha(string committish, CancellationToken cancellationToken);
+
 		/// <summary>
 		/// Checks out a given <paramref name="committish"/>
 		/// </summary>

src/Tgstation.Server.Host/Components/Repository/Repository.cs

@@ -418,5 +418,12 @@ namespace Tgstation.Server.Host.Components.Repository
 				}
 			}, cancellationToken, TaskCreationOptions.LongRunning, TaskScheduler.Current).ConfigureAwait(false);
 		}
+
+		/// <inheritdoc />
+		public Task<bool> IsSha(string committish, CancellationToken cancellationToken) => Task.Factory.StartNew(() =>
+		{
+			var gitObject = repository.Lookup(committish, ObjectType.Commit);
+			return gitObject != null;
+		}, cancellationToken, TaskCreationOptions.LongRunning, TaskScheduler.Current);
 	}
 }