Merge branch 'fix_#637_osc_vc_escape_chars' of https://github.com/lethliel/osc

Pass the filename to the vc script instead of passing its content via
the "-m" parameter. If "osc vc --file <fname>" is issued, it might be
possible that $EDITOR is still opened (if the "vc" script is too old),
which contradicts the --file option's help text. This "break" is acceptable
(just update osc in tandem with the vc script).

osc/commandline.py

@@ -8920,10 +8920,14 @@ Please submit there instead, or use --nodevelproject to force direct submission.
                 cmd_list.append("-m")
                 cmd_list.append(opts.message)
             if opts.file:
-                if not os.path.isfile(opts.file):
+                if len(args) > 1:
+                    raise oscerr.WrongOptions('--file and file_with_comment are mutually exclusive')
+                elif not os.path.isfile(opts.file):
                     raise oscerr.WrongOptions('\'%s\': is no file' % opts.file)
-                cmd_list.append("-m")
-                cmd_list.append(open(opts.file).read().strip())
+                args = list(args)
+                if not args:
+                    cmd_list.append('')
+                cmd_list.append(opts.file)
 
             if opts.just_edit:
                 cmd_list.append("-e")