When failing to load an extension, show where Hg tried to load it from.

mercurial/extensions.py

@@ -78,8 +78,12 b' def loadall(ui):'
         except (util.SignalInterrupt, KeyboardInterrupt):
             raise
         except Exception, inst:
-            ui.warn(_("*** failed to import extension %s: %s\n") %
-                    (name, inst))
+            if path:
+                ui.warn(_("*** failed to import extension %s from %s: %s\n")
+                        % (name, path, inst))
+            else:
+                ui.warn(_("*** failed to import extension %s: %s\n")
+                        % (name, inst))
             if ui.print_exc():
                 return 1
 

tests/test-bad-extension

@@ -7,5 +7,7 b" echo '[extensions]' >> $HGRCPATH"
 echo "gpg =" >> $HGRCPATH
 echo "hgext.gpg =" >> $HGRCPATH
 echo "badext = $abspath" >> $HGRCPATH
+echo "badext2 =" >> $HGRCPATH
 
-hg -q help help
+hg -q help help 2>&1 | python -c \
+  "import sys; sys.stdout.write(sys.stdin.read().replace('$abspath', '.../badext.py'))"

tests/test-bad-extension.out

@@ -1,4 +1,5 b''
-*** failed to import extension badext: bit bucket overflow
+*** failed to import extension badext from .../badext.py: bit bucket overflow
+*** failed to import extension badext2: No module named badext2
 hg help [COMMAND]
 
 show help for a command, extension, or list of commands