RCommand: fix bash-over-ssh's duplicate command echo with --noediting (real fix for issue #64)

Root cause, finally isolated correctly: a *previous* attempt at this
fix (bracketed-paste mode aside, which was a real, separate, already-
fixed bug) modified the wrong code path -- it touched echoshell,
which only affects the same-domain "local shell" exp_spawnv()
shortcut (used when the target machine name matches this host's own
hostname, e.g. niobium), not the real-ssh path (used for anything
else, e.g. localhost) where the bug actually lives. Confirmed directly
side by side: the identical long-command echo test never reproduces
the duplicate over the local-shell shortcut, 100% of the time over
real ssh.

The actual remote invocation for a real ssh connection is built
separately (a fixed argv array ending in "-i", not the echoshell
string), and was never touched by the earlier attempt. Disabling
readline there (bash's actual flag: --noediting) is the real fix --
confirmed via 10/10 repeated live runs over a real ssh connection, each
now completing a full ~20KB simulated eccejobmonitor stream cleanly
(previously 100% failure, truncated after the very first read).

One wrinkle found empirically: bash requires GNU long options before
short options in the same invocation ("bash -i --noediting" errors
with "--: invalid option"; "bash --noediting -i" is the working form) --
confirmed directly before landing the fix.

Regression-tested: fileOp/cd/execbg all still pass over the same
connection with this change.

This should make the launcher's new "Use csh/tcsh" checkbox (added
minutes earlier as a stopgap, before this fix was found) unnecessary
for its original purpose, though it's harmless to leave in place as a
troubleshooting toggle.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: andy

src/comm/rcommand/RCommand.C

@@ -379,7 +379,28 @@ string RCommand::shellCommand(const string& remShell, const string& machine,
   string echoshell = "echo +hi+ && " + locShell + " -f";
 
   static const char* minl  =  "-l";
-  static const char* cmd[] = {"echo", "+hi+", "&&", "", "-i", 0};
+  // bash spawned this way (as the remote command of a real ssh session,
+  // as opposed to the same-domain "local shell" exp_spawnv() shortcut
+  // built from echoshell above) has a confirmed, reproducible bug:
+  // readline duplicates a trailing fragment of a long command line's
+  // echo a second time after the real, correct echo -- and since a
+  // caller's command text can legitimately contain its own "did this
+  // die" marker as a literal substring (e.g. job monitoring's "echo
+  // eccejobmonitor_went_bye_bye"), that duplicate reads as a false
+  // "command already finished" signal. Confirmed live, directly: the
+  // identical test over the "local shell" shortcut (which also runs
+  // bash, just not through ssh) never reproduces this -- so it's
+  // specific to interactive bash under a real pty-forwarded ssh
+  // session, not bash in general. --noediting disables readline
+  // entirely while keeping -i (interactive: reads ~/.bashrc, sets a
+  // default prompt, etc.) intact.
+  // bash requires GNU long options before short options in the same
+  // invocation ("bash -i --noediting" errors with "--: invalid option";
+  // "bash --noediting -i" is the form that actually works) -- confirmed
+  // directly.
+  static const char* cmdBash[] = {"echo", "+hi+", "&&", "", "--noediting", "-i", 0};
+  static const char* cmdOther[] = {"echo", "+hi+", "&&", "", "-i", 0};
+  const char** cmd = (locShell == "bash") ? cmdBash : cmdOther;
   cmd[3] = strdup(locShell.c_str());
 
   // ssh verbose flag for recognizing authentication success/failure