Tag Boost.MPI python impls properly to avoid name clash
https://github.com/boostorg/mpi/issues/112

--- a/boostcpp.jam
+++ b/boostcpp.jam
@@ -185,7 +185,7 @@
 
 rule tag ( name : type ? : property-set )
 {
-    if $(type) in STATIC_LIB SHARED_LIB IMPORT_LIB
+    if $(type) in STATIC_LIB SHARED_LIB IMPORT_LIB PYTHON_EXTENSION
     {
         local args = $(.format-name-args) ;
         if $(layout) = versioned
@@ -223,7 +223,7 @@
 {
     local result = $(name) ;
 
-    if $(type) in STATIC_LIB SHARED_LIB IMPORT_LIB
+    if $(type) in STATIC_LIB SHARED_LIB IMPORT_LIB PYTHON_EXTENSION
     {
         # Add Python version suffix
 
--- a/libs/mpi/build/Jamfile.v2
+++ b/libs/mpi/build/Jamfile.v2
@@ -58,13 +58,13 @@
 rule python-tag ( name : type ? : property-set )
 {
     local result = $(name) ;
-    if $(type) in STATIC_LIB SHARED_LIB IMPORT_LIB
+    if $(type) in STATIC_LIB SHARED_LIB IMPORT_LIB PYTHON_EXTENSION
     {
         local version = [ $(property-set).get <python> ] ;
         local lib-suffix = [ version-suffix $(version) ] ;
         result = $(result)$(lib-suffix) ;
     }
-    if $(type) in STATIC_LIB SHARED_LIB IMPORT_LIB && $(PYTHON_ID)
+    if $(type) in STATIC_LIB SHARED_LIB IMPORT_LIB PYTHON_EXTENSION && $(PYTHON_ID)
     {
         result = $(result)-$(PYTHON_ID) ;
     }
@@ -168,6 +168,8 @@
                 <link>shared:<define>BOOST_PYTHON_DYN_LINK=1
                 <link>shared <runtime-link>shared
                 <python-debugging>on:<define>BOOST_DEBUG_PYTHON
+                -<tag>@$(BOOST_JAMROOT_MODULE)%$(BOOST_JAMROOT_MODULE).tag
+                <tag>@$(__name__).python-tag
               ;
 
             mpi_python_libs = boost_mpi_python mpi ;