completion: add case-insensitive match of pseudorefs

When GIT_COMPLETION_IGNORE_CASE is set, also allow lowercase completion
text like "head" to match uppercase HEAD and other pseudorefs.

Signed-off-by: Alison Winters <alisonatwork@outlook.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/completion/git-completion.bash

@@ -722,6 +722,7 @@ __git_refs ()
 	local format refs
 	local pfx="${3-}" cur_="${4-$cur}" sfx="${5-}"
 	local match="${4-}"
+	local umatch="${4-}"
 	local fer_pfx="${pfx//\%/%%}" # "escape" for-each-ref format specifiers
 
 	__git_find_repo_path
@@ -745,12 +746,19 @@ __git_refs ()
 		fi
 	fi
 
+	if test "${GIT_COMPLETION_IGNORE_CASE:+1}" = "1"
+	then
+		# uppercase with tr instead of ${match,^^} for bash 3.2 compatibility
+		umatch=$(echo "$match" | tr a-z A-Z 2>/dev/null || echo "$match")
+	fi
+
 	if [ "$list_refs_from" = path ]; then
 		if [[ "$cur_" == ^* ]]; then
 			pfx="$pfx^"
 			fer_pfx="$fer_pfx^"
 			cur_=${cur_#^}
 			match=${match#^}
+			umatch=${umatch#^}
 		fi
 		case "$cur_" in
 		refs|refs/*)
@@ -761,7 +769,7 @@ __git_refs ()
 		*)
 			for i in HEAD FETCH_HEAD ORIG_HEAD MERGE_HEAD REBASE_HEAD CHERRY_PICK_HEAD; do
 				case "$i" in
-				$match*)
+				$match*|$umatch*)
 					if [ -e "$dir/$i" ]; then
 						echo "$pfx$i$sfx"
 					fi
@@ -795,7 +803,7 @@ __git_refs ()
 	*)
 		if [ "$list_refs_from" = remote ]; then
 			case "HEAD" in
-			$match*)	echo "${pfx}HEAD$sfx" ;;
+			$match*|$umatch*)	echo "${pfx}HEAD$sfx" ;;
 			esac
 			__git for-each-ref --format="$fer_pfx%(refname:strip=3)$sfx" \
 				${GIT_COMPLETION_IGNORE_CASE+--ignore-case} \
@@ -804,7 +812,7 @@ __git_refs ()
 		else
 			local query_symref
 			case "HEAD" in
-			$match*)	query_symref="HEAD" ;;
+			$match*|$umatch*)	query_symref="HEAD" ;;
 			esac
 			__git ls-remote "$remote" $query_symref \
 				"refs/tags/$match*" "refs/heads/$match*" \

t/t9902-completion.sh

@@ -2270,6 +2270,21 @@ test_expect_success 'checkout matches case insensitively with GIT_COMPLETION_IGN
 	)
 '
 
+test_expect_success 'checkout completes pseudo refs' '
+	test_completion "git checkout H" <<-\EOF
+	HEAD Z
+	EOF
+'
+
+test_expect_success 'checkout completes pseudo refs case insensitively with GIT_COMPLETION_IGNORE_CASE' '
+	(
+		GIT_COMPLETION_IGNORE_CASE=1 &&
+		test_completion "git checkout h" <<-\EOF
+		HEAD Z
+		EOF
+	)
+'
+
 test_expect_success 'git -C <path> checkout uses the right repo' '
 	test_completion "git -C subdir -C subsubdir -C .. -C ../otherrepo checkout b" <<-\EOF
 	branch-in-other Z