scribble latex: work around `\href{...#...}{...}' as a macro argument

The `math' document build was failing because `\marginpar' does not
like `\href{...#...}{...}' as an argument.

original commit: 24f358a5d7afca40fcf734af94c2c94a80a817dc

collects/scribble/latex-render.rkt

@@ -391,12 +391,19 @@
                   (let ([v (car l)])
                     (cond
                      [(target-url? v)
-                      (printf "\\href{~a}{" (regexp-replace* #rx"%"
+                      (define target (regexp-replace* #rx"%"
                                                       (let ([p (target-url-addr v)])
                                                         (if (path? p)
                                                             (path->string p)
                                                             p))
                                                       "\\\\%"))
+                      (if (regexp-match? #rx"^[^#]*#[^#]*$" target)
+                          ;; work around a problem with `\href' as an
+                          ;; argument to other macros, such as `\marginpar':
+                          (let ([l (string-split target "#")])
+                            (printf "\\Shref{~a}{~a}{" (car l) (cadr l)))
+                          ;; normal:
+                          (printf "\\href{~a}{" target))
                       (loop (cdr l) #t)
                       (printf "}")]
                      [(color-property? v)

collects/scribble/scribble.tex

@@ -190,6 +190,10 @@
 % Helper for box-mode macros:
 \newcommand{\Svcenter}[1]{$\vcenter{#1}$}
 
+% Helper to work around a problem with "#"s for URLs within \href
+% within other macros:
+\newcommand{\Shref}[3]{\href{#1\##2}{#3}}
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
 % Scribble then generates the following: