Small fix to build script (resend)

This seems to have fallen on the floor... Original send date: Thu, 1 Jun 2017 19:43:43 +1000

Avoid going splat if --depth is not given

Commit 6b4a9c5 indroduced the --depth parameter to limit the commit history pulled by when cloning, giving a nice speedup. But in the process it broke running without the --depth parameter. The first invocation of './build --main-git' works fine, but the second falls over like so:

fatal: No such remote or remote group: media_tree/master Can't update from the upstream tree at ./build line 430.

The fix is to check whether that remote has been defined before trying to update from it.

---
 build | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

index a4cd38e..d7f51c2 100755
@@ -427,8 +427,13 @@ if (@git == 2) {
 			}
 		}
 	} elsif ($workdir eq "") {
-		system("git --git-dir media/.git remote update '$rname/$git[1]'") == 0
-			or die "Can't update from the upstream tree";
+		if (check_git("remote", "$rname/$git[1]")) {
+			system("git --git-dir media/.git remote update '$rname/$git[1]'") == 0
+				or die "Can't update from the upstream tree";
+		} else {
+			system("git --git-dir media/.git remote update origin") == 0
+				or die "Can't update from the upstream tree";
+		}
 	}
 
 	if ($workdir eq "") {