test-lib: allow selecting tests by substring/glob with --run

Many of our test scripts have several "setup" tests.  It's a lot easier
to say

   ./t0050-filesystem.sh --run=setup,9

in order to run all the setup tests as well as test #9, than it is to
track down what all the setup tests are and enter all their numbers in
the list.  Also, I often find myself wanting to run just one or a couple
tests from the test file, but I don't know the numbering of any of the
tests -- to get it I either have to first run the whole test file (or
start counting by hand or figure out some other clever but non-obvious
tricks).  It's really convenient to be able to just look at the test
description(s) and then run

   ./t6416-recursive-corner-cases.sh --run=symlink

or

   ./t6402-merge-rename.sh --run='setup,unnecessary update'

Add such an ability to test selection which relies on merely matching
against the test description.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/test-lib.sh b/t/test-lib.sh
index ef31f40..72b88df 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -769,15 +769,17 @@
 }
 
 match_test_selector_list () {
+	operation="$1"
+	shift
 	title="$1"
 	shift
 	arg="$1"
 	shift
 	test -z "$1" && return 0
 
-	# Both commas and whitespace are accepted as separators.
+	# Commas are accepted as separators.
 	OLDIFS=$IFS
-	IFS=' 	,'
+	IFS=','
 	set -- $1
 	IFS=$OLDIFS
 
@@ -805,13 +807,13 @@
 			*-*)
 				if expr "z${selector%%-*}" : "z[0-9]*[^0-9]" >/dev/null
 				then
-					echo "error: $title: invalid non-numeric in range" \
+					echo "error: $operation: invalid non-numeric in range" \
 						"start: '$orig_selector'" >&2
 					exit 1
 				fi
 				if expr "z${selector#*-}" : "z[0-9]*[^0-9]" >/dev/null
 				then
-					echo "error: $title: invalid non-numeric in range" \
+					echo "error: $operation: invalid non-numeric in range" \
 						"end: '$orig_selector'" >&2
 					exit 1
 				fi
@@ -819,9 +821,11 @@
 			*)
 				if expr "z$selector" : "z[0-9]*[^0-9]" >/dev/null
 				then
-					echo "error: $title: invalid non-numeric in test" \
-						"selector: '$orig_selector'" >&2
-					exit 1
+					case "$title" in *${selector}*)
+						include=$positive
+						;;
+					esac
+					continue
 				fi
 		esac
 
@@ -1031,7 +1035,7 @@
 		skipped_reason="GIT_SKIP_TESTS"
 	fi
 	if test -z "$to_skip" && test -n "$run_list" &&
-	   ! match_test_selector_list '--run' $test_count "$run_list"
+	   ! match_test_selector_list '--run' "$1" $test_count "$run_list"
 	then
 		to_skip=t
 		skipped_reason="--run"