Add `skip_setsid` option to nsjail for sbox.

ABFS project uses the process group to trace all the
file-system activities of a given build command.
The assumption is that the build commands do not change the
process group, otherwise some of the file operations can be
missed.

Bug: 376530561
Change-Id: Iff32df924e1cb20be2ce4dfe3355d833c0fb9e8e
diff --git a/android/rule_builder.go b/android/rule_builder.go
index 403c184..a157386 100644
--- a/android/rule_builder.go
+++ b/android/rule_builder.go
@@ -611,6 +611,7 @@
 		nsjailCmd.WriteString(" -m none:/tmp:tmpfs:size=1073741824") // 1GB, should be enough
 		nsjailCmd.WriteString(" -D nsjail_build_sandbox")
 		nsjailCmd.WriteString(" --disable_rlimits")
+		nsjailCmd.WriteString(" --skip_setsid") // ABFS relies on process-groups to track file operations
 		nsjailCmd.WriteString(" -q")
 		nsjailCmd.WriteString(" -- ")
 		nsjailCmd.WriteString("/bin/bash -c ")