Since commit

  56bcdbea2bed ("Let gdb.execute handle multi-line commands")

command repetition after using the `gdb.execute` Python function
fails (the previous command is not repeated anymore). This happens
because read_command_lines_1 sets dont_repeat, but the call to
prevent_dont_repeat in execute_gdb_command is later.

The fix is to move the call to prevent_dont_repeat to the beginning of
the function.

Tested on my laptop (ArchLinux-x86_64)

gdb/ChangeLog:

    PR python/#23714
    * gdb/python/python.c (execute_gdb_command): call prevent_dont_repeat
    earlier to avoid affecting dont_repeat

gdb/testuite/ChangeLog:

    PR python/#23714
    * gdb.python/python.exp: Test gdb.execute("show commands").
---
 gdb/python/python.c                 | 3 ++-
 gdb/testsuite/gdb.python/python.exp | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)