Add separate UsePty flag for CmdObj

This decouples StreamOutput from whether a PTY is used. In most cases we just
want to see the output in the log window, but don't have to use a PTY, e.g. for
the bisect commands.

This has the implication that custom commands that are using "stream: true" no
longer use a PTY. In most cases that's probably a good thing, but we're going to
add a separate pty config for those who really wanted this.

pkg/commands/oscommands/cmd_obj.go

@@ -22,6 +22,9 @@ type CmdObj struct {
 	// see StreamOutput()
 	streamOutput bool
 
+	// see UsePty()
+	usePty bool
+
 	// see IgnoreEmptyError()
 	ignoreEmptyError bool
 
@@ -125,6 +128,19 @@ func (self *CmdObj) ShouldStreamOutput() bool {
 	return self.streamOutput
 }
 
+// when you call this, then call Run(), we'll use a PTY to run the command. Only
+// has an effect if StreamOutput() was also called. Ignored on Windows.
+func (self *CmdObj) UsePty() *CmdObj {
+	self.usePty = true
+
+	return self
+}
+
+// returns true if UsePty() was called
+func (self *CmdObj) ShouldUsePty() bool {
+	return self.usePty
+}
+
 // if you call this before ShouldStreamOutput we'll consider an error with no
 // stderr content as a non-error. Not yet supported for Run or RunWithOutput (
 // but adding support is trivial)
@@ -172,6 +188,7 @@ func (self *CmdObj) RunAndProcessLines(onLine func(line string) (bool, error)) e
 
 func (self *CmdObj) PromptOnCredentialRequest(task gocui.Task) *CmdObj {
 	self.credentialStrategy = PROMPT
+	self.usePty = true
 	self.task = task
 
 	return self

pkg/commands/oscommands/cmd_obj_runner.go

@@ -238,7 +238,13 @@ func (self *cmdObjRunner) runAndStreamAux(
 	var stderr bytes.Buffer
 	cmd.Stderr = io.MultiWriter(cmdWriter, &stderr)
 
-	handler, err := self.getCmdHandlerPty(cmd)
+	var handler *cmdHandler
+	var err error
+	if cmdObj.ShouldUsePty() {
+		handler, err = self.getCmdHandlerPty(cmd)
+	} else {
+		handler, err = self.getCmdHandlerNonPty(cmd)
+	}
 	if err != nil {
 		return err
 	}