Add release note for FAB-17725

Signed-off-by: Matthew Sykes <sykesmat@us.ibm.com>

release_notes/v2.1.0.md

@@ -0,0 +1,29 @@
+
+Fixes
+-----
+
+**FAB-17725: Omit go.mod and go.sum from package when not in module mode**
+
+In certain environments, it's possible to package chaincode that is structured
+as a module from an active GOPATH. This often happens when the path provided
+to the package command is an import path resolvable from the GOPATH instead of
+a file system path.
+
+If the package can successfully build in the packaging environment from the
+import path, the chaincode dependencies are calculated and packaged from the
+GOPATH for compilation as a traditional go package.
+
+In this scenario where the code at the import path is structured as a module,
+the go.mod would be included in the chaincode package as packaging always
+includes all non-hidden files in the top level folder of the import path.
+
+On the server, the presence of the go.mod implies that the build process
+should execute in module mode. When the dependencies have been vendored in the
+module, the build uses -mod=vendor flag to indicate the module requirements
+should be satisfied from the vendor folder.  Unfortunately, since the
+chaincode dependencies were packaged using GOPATH mode instead of module mode,
+there are some metadata files missing from the vendor folder that are expected
+by the module mode build process.
+
+To help prevent this from occurring, we will explicitly omit go.mod and go.sum
+from top level folder of chaincode that is not packaged in module mode.