The Debian packaging of foo is maintained in git, using the merging
workflow described in dgit-maint-merge(7).  There isn't a patch
queue that can be represented as a quilt series.

A detailed breakdown of the changes is available from their
canonical representation - git commits in the packaging repository.
For example, to see the changes made by the Debian maintainer in
the first upload of upstream version 0.14.1, (when this package first 
used dgit) you could use:

   % git clone https://git.dgit.debian.org/libopencsd
   % cd libopencsd
   % git log --oneline 0.14.1..debian/0.14.1-1 -- . ':!debian'

(If you have dgit, use `dgit clone foo`, rather than plain `git
clone`.)

A single combined diff, containing all the changes, follows.
--- libopencsd-0.14.4.orig/decoder/source/etmv4/trc_pkt_decode_etmv4i.cpp
+++ libopencsd-0.14.4/decoder/source/etmv4/trc_pkt_decode_etmv4i.cpp
@@ -525,7 +525,7 @@ ocsd_err_t TrcPktDecodeEtmV4I::decodePac
         //resp = OCSD_RESP_FATAL_INVALID_DATA;
 #endif
         err = OCSD_ERR_UNSUPP_DECODE_PKT;
-        LogError(ocsdError(sev, err, "Data trace releated, unsupported packet type."));
+        LogError(ocsdError(sev, err, "Data trace related, unsupported packet type."));
         }
         break;
 
