cvsimport: setup indexes correctly for ancestors and incremental imports

Two bugs had slipped in the "keep one index per branch during import"
patch. Both incremental imports and new branches would see an
empty tree for their initial commit. Now we cover all the relevant
cases, checking whether we actually need to setup the index before
preparing the actual commit, and doing it.
Signed-off-by: NMartin Langhoff <martin@catalyst.net.nz>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

git-cvsimport.perl

@@ -17,7 +17,7 @@
 use warnings;
 use Getopt::Std;
 use File::Spec;
-use File::Temp qw(tempfile);
+use File::Temp qw(tempfile tmpnam);
 use File::Path qw(mkpath);
 use File::Basename qw(basename dirname);
 use Time::Local;
@@ -467,12 +467,8 @@ ($$)
 $orig_git_index = $ENV{GIT_INDEX_FILE} if exists $ENV{GIT_INDEX_FILE};
 
 my %index; # holds filenames of one index per branch
-{   # init with an index for origin
-    my ($fh, $fn) = tempfile('gitXXXXXX', SUFFIX => '.idx',
-			     DIR => File::Spec->tmpdir());
-    close ($fh);
-    $index{$opt_o} = $fn;
-}
+$index{$opt_o} = tmpnam();
+
 $ENV{GIT_INDEX_FILE} = $index{$opt_o};
 unless(-d $git_dir) {
 	system("git-init-db");
@@ -502,10 +498,7 @@ ($$)
 
 	# populate index
 	unless ($index{$last_branch}) {
-	    my ($fh, $fn) = tempfile('gitXXXXXX', SUFFIX => '.idx',
-				     DIR => File::Spec->tmpdir());
-	    close ($fh);
-	    $index{$last_branch} = $fn;
+	    $index{$last_branch} = tmpnam();
 	}
 	$ENV{GIT_INDEX_FILE} = $index{$last_branch};
 	system('git-read-tree', $last_branch);
@@ -818,16 +811,28 @@ sub commit {
 		if(($ancestor || $branch) ne $last_branch) {
 			print "Switching from $last_branch to $branch\n" if $opt_v;
 			unless ($index{$branch}) {
-			    my ($fh, $fn) = tempfile('gitXXXXXX', SUFFIX => '.idx',
-						     DIR => File::Spec->tmpdir());
-			    close ($fh);
-			    $index{$branch} = $fn;
+			    $index{$branch} = tmpnam();
 			    $ENV{GIT_INDEX_FILE} = $index{$branch};
-			    system("git-read-tree", $branch);
+			}
+			if ($ancestor) {
+			    system("git-read-tree", $ancestor);
 			    die "read-tree failed: $?\n" if $?;
 			} else {
+			    unless ($index{$branch}) {
+				$index{$branch} = tmpnam();
+				$ENV{GIT_INDEX_FILE} = $index{$branch};
+				system("git-read-tree", $branch);
+				die "read-tree failed: $?\n" if $?;
+			    }
+			}
+		} else {
+			# just in case
+			unless ($index{$branch}) {
+			    $index{$branch} = tmpnam();
 			    $ENV{GIT_INDEX_FILE} = $index{$branch};
-		        }
+			    system("git-read-tree", $branch);
+			    die "read-tree failed: $?\n" if $?;
+			}
 		}
 		$last_branch = $branch if $branch ne $last_branch;
 		$state = 9;