Fix off-by-one error in appveyor-install.ps1 and use branch name from APPVEYOR_REPO_BRANCH in case of AppVeyor build in UpdateAssemblyInfo.

BuildTools/UpdateAssemblyInfo/Main.cs

@@ -197,7 +197,12 @@ namespace UpdateAssemblyInfo
 				if (Directory.Exists(".git")) {
 					try {
 						ReadRevisionNumberFromGit();
-						ReadBranchNameFromGit();
+						string appVeyorBranch = Environment.GetEnvironmentVariable("APPVEYOR_REPO_BRANCH");
+						// AppVeyor uses a repository with detached head.
+						if (string.IsNullOrWhiteSpace(appVeyorBranch))
+							ReadBranchNameFromGit();
+						else
+							gitBranchName = appVeyorBranch;
 					} catch (Exception ex) {
 						Console.WriteLine(ex.ToString());
 					}

BuildTools/appveyor-install.ps1

@@ -9,7 +9,7 @@ if ($env:APPVEYOR_REPO_BRANCH -ne 'master') {
 	$branch = "";
 }
 
-$build = git rev-list --count "$baseCommitHash..HEAD";
+$build = [Int32]::Parse((git rev-list --count "$baseCommitHash..HEAD")) + 1;
 
 $newVersion="$majorVersion.$minorVersion.$revision.$build";
 $env:ilspy_version_number=$newVersion;