Bug: git log -L manpage claims regexes are supported, but they are not

Context:

   $ git version
git version 2.25.1

   $ git log -L ^/bootstrap-sass/,+2 Gemfile
fatal: -L argument not 'start,end:file' or ':funcname:file': 
^/bootstrap-sass/,+2

I expected the above to work, based on the contents of `git help log`, which describes the regex format.

This regex format works correctly in `git blame -L`, and it appears the manpage was copied across but not the implementation.

$ git help log

        -L <start>,<end>:<file>, -L :<funcname>:<file>
            Trace the evolution of the line range given by 
"<start>,<end>" (or the function name regex <funcname>) within the 
<file>. You may not give any pathspec limiters. This is
            currently limited to a walk starting from a single revision, 
i.e., you may only give zero or one positive revision arguments, and 
<start> and <end> (or <funcname>) must
            exist in the starting revision. You can specify this option 
more than once. Implies --patch. Patch output can be suppressed using 
--no-patch, but other diff formats (namely
            --raw, --numstat, --shortstat, --dirstat, --summary, 
--name-only, --name-status, --check) are not currently implemented.

            <start> and <end> can take one of these forms:

            •   number

                If <start> or <end> is a number, it specifies an 
absolute line number (lines count from 1).

            •   /regex/

                This form will use the first line matching the given 
POSIX regex. If <start> is a regex, it will search from the end of the 
previous -L range, if any, otherwise from the
                start of file. If <start> is “^/regex/”, it will search 
from the start of file. If <end> is a regex, it will search starting at 
the line given by <start>.

            •   +offset or -offset

                This is only valid for <end> and will specify a number 
of lines before or after the line given by <start>.

            If “:<funcname>” is given in place of <start> and <end>, it 
is a regular expression that denotes the range from the first funcname 
line that matches <funcname>, up to the
            next funcname line. “:<funcname>” searches from the end of 
the previous -L range, if any, otherwise from the start of file. 
“^:<funcname>” searches from the start of file.