record: exiting editor with non-zero status should not stop recording session

Before this patch, exiting a hunk edit in record with a non-zero status lead
to the end of the recording session, losing previously-selected hunks to record.
This patch introduces the more desirable behavior of warning the user and
continuing the recording session.

mercurial/patch.py

@@ -1023,9 +1023,11 b' the hunk is left unchanged.'
                     f.close()
                     # Start the editor and wait for it to complete
                     editor = ui.geteditor()
-                    ui.system("%s \"%s\"" % (editor, patchfn),
-                              environ={'HGUSER': ui.username()},
-                              onerr=util.Abort, errprefix=_("edit failed"))
+                    ret = ui.system("%s \"%s\"" % (editor, patchfn),
+                                    environ={'HGUSER': ui.username()})
+                    if ret != 0:
+                        ui.warn(_("editor exited with exit code %d\n") % ret)
+                        continue
                     # Remove comment lines
                     patchfp = open(patchfn)
                     ncpatchfp = cStringIO.StringIO()

tests/test-commit-interactive.t

@@ -1291,6 +1291,33 b' Malformed patch - error handling'
   abort: error parsing patch: unhandled transition: range -> range
   [255]
 
+Exiting editor with status 1, ignores the edit but does not stop the recording
+session
+
+  $ HGEDITOR=false hg commit -i <<EOF
+  > y
+  > e
+  > n
+  > EOF
+  diff --git a/editedfile b/editedfile
+  1 hunks, 3 lines changed
+  examine changes to 'editedfile'? [Ynesfdaq?] y
+  
+  @@ -1,3 +1,3 @@
+  -This is the first line
+  -This change will be committed
+  -This is the third line
+  +This change will not be committed
+  +This is the second line
+  +This line has been added
+  record this change to 'editedfile'? [Ynesfdaq?] e
+  
+  editor exited with exit code 1
+  record this change to 'editedfile'? [Ynesfdaq?] n
+  
+  no changes to record
+
+
 random text in random positions is still an error
 
   $ cat > editor.sh << '__EOF__'