convert: Safer handling of $Id$ contraction.

The code to contract $Id:xxxxx$ strings could eat an arbitrary amount
of source text if the terminating $ was lost. It now refuses to
contract $Id:xxxxx$ strings spanning multiple lines.

Signed-off-by: Henrik Grubbström <grubba@grubba.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index 6cb8d60..29438c5 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -65,17 +65,21 @@
 		echo "\$Id:NoSpaceAtFront \$"
 		echo "\$Id:NoSpaceAtEitherEnd\$"
 		echo "\$Id: NoTerminatingSymbol"
+		echo "\$Id: Foreign Commit With Spaces \$"
+		echo "\$Id: NoTerminatingSymbolAtEOF"
 	} > expanded-keywords &&
 
 	{
 		echo "File with expanded keywords"
-		echo "\$Id: 4f21723e7b15065df7de95bd46c8ba6fb1818f4c \$"
-		echo "\$Id: 4f21723e7b15065df7de95bd46c8ba6fb1818f4c \$"
-		echo "\$Id: 4f21723e7b15065df7de95bd46c8ba6fb1818f4c \$"
-		echo "\$Id: 4f21723e7b15065df7de95bd46c8ba6fb1818f4c \$"
-		echo "\$Id: 4f21723e7b15065df7de95bd46c8ba6fb1818f4c \$"
-		echo "\$Id: 4f21723e7b15065df7de95bd46c8ba6fb1818f4c \$"
+		echo "\$Id: fd0478f5f1486f3d5177d4c3f6eb2765e8fc56b9 \$"
+		echo "\$Id: fd0478f5f1486f3d5177d4c3f6eb2765e8fc56b9 \$"
+		echo "\$Id: fd0478f5f1486f3d5177d4c3f6eb2765e8fc56b9 \$"
+		echo "\$Id: fd0478f5f1486f3d5177d4c3f6eb2765e8fc56b9 \$"
+		echo "\$Id: fd0478f5f1486f3d5177d4c3f6eb2765e8fc56b9 \$"
+		echo "\$Id: fd0478f5f1486f3d5177d4c3f6eb2765e8fc56b9 \$"
 		echo "\$Id: NoTerminatingSymbol"
+		echo "\$Id: fd0478f5f1486f3d5177d4c3f6eb2765e8fc56b9 \$"
+		echo "\$Id: NoTerminatingSymbolAtEOF"
 	} > expected-output &&
 
 	git add expanded-keywords &&