Produce absolute path per api doc when reading version file

Fixes #573

Author: AArnott

src/NerdBank.GitVersioning/LibGit2/LibGit2VersionFile.cs

@@ -59,7 +59,8 @@ internal LibGit2VersionFile(LibGit2Context context)
 
                     if (result is object)
                     {
-                        actualDirectory = searchDirectory;
+                        IBelongToARepository commitAsRepoMember = commit;
+                        actualDirectory = Path.Combine(commitAsRepoMember.Repository.Info.WorkingDirectory, searchDirectory);
                         return result;
                     }
                 }
@@ -125,7 +126,8 @@ internal LibGit2VersionFile(LibGit2Context context)
                     }
                     else if (result is object)
                     {
-                        actualDirectory = searchDirectory;
+                        IBelongToARepository commitAsRepoMember = commit;
+                        actualDirectory = Path.Combine(commitAsRepoMember.Repository.Info.WorkingDirectory, searchDirectory);
                         return result;
                     }
                 }

src/NerdBank.GitVersioning/Managed/ManagedVersionFile.cs

@@ -85,7 +85,7 @@ public ManagedVersionFile(GitContext context)
                     if (result is object)
                     {
                         finalResult = result;
-                        actualDirectory = searchDirectory;
+                        actualDirectory = Path.Combine(this.Context.WorkingTreePath, searchDirectory);
                     }
                 }
 
@@ -158,7 +158,7 @@ public ManagedVersionFile(GitContext context)
 
                     if (result is object)
                     {
-                        actualDirectory = searchDirectory;
+                        actualDirectory = Path.Combine(this.Context.WorkingTreePath, searchDirectory);
                         finalResult = result;
                     }
                 }