Local `commit-msg` doesn't work in conjunction with global `prepare-commit-msg` - bash

Question

When I have my global git hooks directory (which contains just a prepare-commit-msg hook) set up in config, my local commit-msg doesn't run (although the global hook does). However, when I disable the global prepare-commit-msg hook (by commenting out core.hookspath in gitconfig), the local commit-msg hook works just fine.
~/dotfiles/git-hooks/prepare-commit-msg
#!/usr/bin/env bash
pcregrep -Mv '(# Please.*|# with.*|^#$\n(?!#)|^#$(?=\n# On))' $1 > /tmp/msg && cat /tmp/msg > $1
./.git/hooks/commit-msg (Gerrit's hook to add change-id's if necessary, trimmed to remove license comments)
#!/bin/sh
...
unset GREP_OPTIONS
CHANGE_ID_AFTER="Bug|Depends-On|Issue|Test|Feature|Fixes|Fixed"
MSG="$1"
# Check for, and add if missing, a unique Change-Id
#
add_ChangeId() {
clean_message=`sed -e '
/^diff --git .*/{
s///
q
}
/^Signed-off-by:/d
/^#/d
' "$MSG" | git stripspace`
if test -z "$clean_message"
then
return
fi
# Do not add Change-Id to temp commits
if echo "$clean_message" | head -1 | grep -q '^\(fixup\|squash\)!'
then
return
fi
if test "false" = "`git config --bool --get gerrit.createChangeId`"
then
return
fi
# Does Change-Id: already exist? if so, exit (no change).
if grep -i '^Change-Id:' "$MSG" >/dev/null
then
return
fi
id=`_gen_ChangeId`
T="$MSG.tmp.$$"
AWK=awk
if [ -x /usr/xpg4/bin/awk ]; then
# Solaris AWK is just too broken
AWK=/usr/xpg4/bin/awk
fi
# Get core.commentChar from git config or use default symbol
commentChar=`git config --get core.commentChar`
commentChar=${commentChar:-#}
# How this works:
# - parse the commit message as (textLine+ blankLine*)*
# - assume textLine+ to be a footer until proven otherwise
# - exception: the first block is not footer (as it is the title)
# - read textLine+ into a variable
# - then count blankLines
# - once the next textLine appears, print textLine+ blankLine* as these
# aren't footer
# - in END, the last textLine+ block is available for footer parsing
$AWK '
BEGIN {
if (match(ENVIRON["OS"], "Windows")) {
RS="\r?\n" # Required on recent Cygwin
}
# while we start with the assumption that textLine+
# is a footer, the first block is not.
isFooter = 0
footerComment = 0
blankLines = 0
}
# Skip lines starting with commentChar without any spaces before it.
/^'"$commentChar"'/ { next }
# Skip the line starting with the diff command and everything after it,
# up to the end of the file, assuming it is only patch data.
# If more than one line before the diff was empty, strip all but one.
/^diff --git / {
blankLines = 0
while (getline) { }
next
}
# Count blank lines outside footer comments
/^$/ && (footerComment == 0) {
blankLines++
next
}
# Catch footer comment
/^\[[a-zA-Z0-9-]+:/ && (isFooter == 1) {
footerComment = 1
}
/]$/ && (footerComment == 1) {
footerComment = 2
}
# We have a non-blank line after blank lines. Handle this.
(blankLines > 0) {
print lines
for (i = 0; i < blankLines; i++) {
print ""
}
lines = ""
blankLines = 0
isFooter = 1
footerComment = 0
}
# Detect that the current block is not the footer
(footerComment == 0) && (!/^\[?[a-zA-Z0-9-]+:/ || /^[a-zA-Z0-9-]+:\/\//) {
isFooter = 0
}
{
# We need this information about the current last comment line
if (footerComment == 2) {
footerComment = 0
}
if (lines != "") {
lines = lines "\n";
}
lines = lines $0
}
# Footer handling:
# If the last block is considered a footer, splice in the Change-Id at the
# right place.
# Look for the right place to inject Change-Id by considering
# CHANGE_ID_AFTER. Keys listed in it (case insensitive) come first,
# then Change-Id, then everything else (eg. Signed-off-by:).
#
# Otherwise just print the last block, a new line and the Change-Id as a
# block of its own.
END {
unprinted = 1
if (isFooter == 0) {
print lines "\n"
lines = ""
}
changeIdAfter = "^(" tolower("'"$CHANGE_ID_AFTER"'") "):"
numlines = split(lines, footer, "\n")
for (line = 1; line <= numlines; line++) {
if (unprinted && match(tolower(footer[line]), changeIdAfter) != 1) {
unprinted = 0
print "Change-Id: I'"$id"'"
}
print footer[line]
}
if (unprinted) {
print "Change-Id: I'"$id"'"
}
}' "$MSG" > "$T" && mv "$T" "$MSG" || rm -f "$T"
}
_gen_ChangeIdInput() {
echo "tree `git write-tree`"
if parent=`git rev-parse "HEAD^0" 2>/dev/null`
then
echo "parent $parent"
fi
echo "author `git var GIT_AUTHOR_IDENT`"
echo "committer `git var GIT_COMMITTER_IDENT`"
echo
printf '%s' "$clean_message"
}
_gen_ChangeId() {
_gen_ChangeIdInput |
git hash-object -t commit --stdin
}
add_ChangeId
~/dotfiles/gitconfig (trimmed) when global hook is enabled.
...
[core]
editor = code -rwg $1:2
excludesfile = /Users/shreyasminocha/.gitignore
compression = 0
hookspath = /Users/shreyasminocha/dotfiles/git-hooks
...
Git version: 2.18.0
Edit: As #phd pointed out in the comments, "The problem is that global hookspath completely takes over local hooks. If the global hookspath is defined local hooks are never consulted. [I had] to create global /Users/shreyasminocha/dotfiles/git-hooks/commit-msg that [would] run local .git/hooks/commit-msg". Confirming duplicate.

Answer 1

Eventually solved this by adding some code to the global hook, just as #phd suggested. It looks for a local hook and runs it if it exists.
Global prepare-commit-msg hook:
#!/usr/bin/env bash
# if a local hook exists, run it
if [ -e ./.git/hooks/prepare-commit-msg ]; then
./.git/hooks/prepare-commit-msg "$#"
fi
if [ -e ./.git/hooks/commit-msg ]; then
./.git/hooks/commit-msg "$#"
fi
# global_hook-related things follow
pcregrep -Mv '(# Please.*|# with.*|^#$\n(?!#)|^#$(?=\n# On))' $1 > /tmp/msg && cat /tmp/msg > $1