From https://ftp.gnu.org/gnu/bash/bash-5.0-patches/bash50-002

Signed-off-by: Pascal de Bruijn <p.debruijn@unilogic.nl>

			     BASH PATCH REPORT
			     =================

Bash-Release:	5.0
Patch-ID:	bash50-002

Bug-Reported-by:	Ante Peric <synthmeat@gmail.com>
Bug-Reference-ID:	<B7E3B567-2467-4F7B-B6B9-CA4E75A9C93F@gmail.com>
Bug-Reference-URL:	http://lists.gnu.org/archive/html/bug-bash/2019-01/msg00095.html

Bug-Description:

When an alias value ends with an unquoted literal tab (not part of a quoted
string or comment), alias expansion cannot correctly detect the end of the
alias value after expanding it.

Patch (apply with `patch -p0'):

*** ../bash-5.0/parser.h	2018-12-28 19:11:18.000000000 -0500
--- b/parser.h	2019-01-11 15:13:03.000000000 -0500
***************
*** 48,51 ****
--- 48,52 ----
  #define PST_REDIRLIST	0x080000	/* parsing a list of redirections preceding a simple command name */
  #define PST_COMMENT	0x100000	/* parsing a shell comment; used by aliases */
+ #define PST_ENDALIAS	0x200000	/* just finished expanding and consuming an alias */
  
  /* Definition of the delimiter stack.  Needed by parse.y and bashhist.c. */
*** ../bash-5.0/parse.y	2019-01-02 13:57:34.000000000 -0500
--- b/parse.y	2019-01-14 08:23:31.000000000 -0500
***************
*** 2558,2567 ****
        pushed_string_list->flags != PSH_DPAREN &&
        (parser_state & PST_COMMENT) == 0 &&
        shell_input_line_index > 0 &&
!       shell_input_line[shell_input_line_index-1] != ' ' &&
        shell_input_line[shell_input_line_index-1] != '\n' &&
        shellmeta (shell_input_line[shell_input_line_index-1]) == 0 &&
        (current_delimiter (dstack) != '\'' && current_delimiter (dstack) != '"'))
      {
        return ' ';	/* END_ALIAS */
      }
--- 2558,2569 ----
        pushed_string_list->flags != PSH_DPAREN &&
        (parser_state & PST_COMMENT) == 0 &&
+       (parser_state & PST_ENDALIAS) == 0 &&	/* only once */
        shell_input_line_index > 0 &&
!       shellblank (shell_input_line[shell_input_line_index-1]) == 0 &&
        shell_input_line[shell_input_line_index-1] != '\n' &&
        shellmeta (shell_input_line[shell_input_line_index-1]) == 0 &&
        (current_delimiter (dstack) != '\'' && current_delimiter (dstack) != '"'))
      {
+       parser_state |= PST_ENDALIAS;
        return ' ';	/* END_ALIAS */
      }
***************
*** 2572,2575 ****
--- 2574,2578 ----
    if (uc == 0 && pushed_string_list && pushed_string_list->flags != PSH_SOURCE)
      {
+       parser_state &= ~PST_ENDALIAS;
        pop_string ();
        uc = shell_input_line[shell_input_line_index];
*** ../bash-5.0/y.tab.c	2019-01-02 13:57:43.000000000 -0500
--- b/y.tab.c	2019-01-14 08:39:23.000000000 -0500
***************
*** 4874,4883 ****
        pushed_string_list->flags != PSH_DPAREN &&
        (parser_state & PST_COMMENT) == 0 &&
        shell_input_line_index > 0 &&
!       shell_input_line[shell_input_line_index-1] != ' ' &&
        shell_input_line[shell_input_line_index-1] != '\n' &&
        shellmeta (shell_input_line[shell_input_line_index-1]) == 0 &&
        (current_delimiter (dstack) != '\'' && current_delimiter (dstack) != '"'))
      {
        return ' ';	/* END_ALIAS */
      }
--- 4874,4885 ----
        pushed_string_list->flags != PSH_DPAREN &&
        (parser_state & PST_COMMENT) == 0 &&
+       (parser_state & PST_ENDALIAS) == 0 &&	/* only once */
        shell_input_line_index > 0 &&
!       shellblank (shell_input_line[shell_input_line_index-1]) == 0 &&
        shell_input_line[shell_input_line_index-1] != '\n' &&
        shellmeta (shell_input_line[shell_input_line_index-1]) == 0 &&
        (current_delimiter (dstack) != '\'' && current_delimiter (dstack) != '"'))
      {
+       parser_state |= PST_ENDALIAS;
        return ' ';	/* END_ALIAS */
      }
***************
*** 4888,4891 ****
--- 4890,4894 ----
    if (uc == 0 && pushed_string_list && pushed_string_list->flags != PSH_SOURCE)
      {
+       parser_state &= ~PST_ENDALIAS;
        pop_string ();
        uc = shell_input_line[shell_input_line_index];
*** ../bash-5.0/patchlevel.h	2016-06-22 14:51:03.000000000 -0400
--- b/patchlevel.h	2016-10-01 11:01:28.000000000 -0400
***************
*** 26,30 ****
     looks for to find the patch level (for the sccs version string). */
  
! #define PATCHLEVEL 1
  
  #endif /* _PATCHLEVEL_H_ */
--- 26,30 ----
     looks for to find the patch level (for the sccs version string). */
  
! #define PATCHLEVEL 2
  
  #endif /* _PATCHLEVEL_H_ */