sagemath#26968: workaround for an ecl race in maxima init

When maxima is initialized a bug in ecl implementation of
`ensure-directories-exist` might result in a runtime error.

As a workaround, in case we get a runtime error we use python to create
the directory and continue with maxima initialization.

Note that for normal usage the directory will already exist within the
user's `DOT_SAGE` so this code will almost never run. However, when
running doctests on CI this occasionally triggers.

src/sage/interfaces/maxima_lib.py

@@ -135,7 +135,19 @@
 ecl_eval("(setq $nolabels t))")
 ecl_eval("(defvar *MAXIMA-LANG-SUBDIR* NIL)")
 ecl_eval("(set-locale-subdir)")
-ecl_eval("(set-pathnames)")
+
+try:
+ ecl_eval("(set-pathnames)")
+except RuntimeError:
+ # Recover from :trac:`26968` by creating `*maxima-objdir*` here.
+ # This cannot be done before calling `(set-pathnames)` since
+ # `*maxima-objdir*` is computed there.
+ maxima_objdir = ecl_eval("*maxima-objdir*").python()[1:-1]
+ import os
+ os.makedirs(maxima_objdir, exist_ok=True)
+ # Call `(set-pathnames)` again to complete its job.
+ ecl_eval("(set-pathnames)")
+
 ecl_eval("(defun add-lineinfo (x) x)")
 ecl_eval('(defun principal nil (cond ($noprincipal (diverg)) ((not pcprntd) (merror "Divergent Integral"))))')
 ecl_eval("(remprop 'mfactorial 'grind)") # don't use ! for factorials (#11539)