tg-tag: handle reflog entries with extra tabs

It's very possible for a reflog entry to have more than one
tab in it.

The actual format of the reflog is one entry per line as detailed
in the `git help update-ref` documentation.

That documentation overlooks the possibility of there being more
than one "TAB" present in a single line (i.e. entry) of a reflog.

The relevant code that actually parses these lines can be found in
the Git file refs/files-backend.c in the show_one_reflog_ent function.

Behave more like the show_one_reflog_ent function when parsing
reflog entry lines to avoid any confusion over where the optional
message actually starts (if it's present).

Toggle the two affected unit tests in t6102 from `test_expect_failure`
to `test_expect_success` as they now pass with this change.

Signed-off-by: Kyle J. McKay <[email protected]>

t/t6102-tag-reflog-tabs.sh

@@ -113,7 +113,7 @@ test_expect_success 'setup main' '
 	test_when_finished test_set_prereq SETUP
 '
 
-test_expect_failure SETUP 'tg tag -g log' '
+test_expect_success SETUP 'tg tag -g log' '
 	cd main &&
 	squish <<-EOT >../expected &&
 		=== 2005-04-07 ===
@@ -135,7 +135,7 @@ test_expect_success LASTOK,SETUP 'tg tag -g --reflog-message matches' '
 	test_cmp ../actual ../expected
 '
 
-test_expect_failure SETUP 'tg tag -g --commit-message log' '
+test_expect_success SETUP 'tg tag -g --commit-message log' '
 	cd main &&
 	squish <<-EOT >../expected2 &&
 		=== 2005-04-07 ===

tg-tag.sh

@@ -505,14 +505,14 @@ if [ -n "$reflog" ]; then
 			while read -r newrev type rest; do
 				stashnum=$(( $stashnum + 1 ))
 				[ "$type" != "missing" ] || continue
-				IFS="$tab" read -r cmmttr msg <<-~EOT~
-					$rest
+				ne= rest2=
+				IFS=">" read -r ne rest2 <<-~EOT~ || :
+					${rest}X
+					~EOT~
+				es= ez= msg=
+				read -r es ez msg <<-~EOT~ || :
+					${rest2%X}
 					~EOT~
-				ne="${cmmttr% *}"
-				ne="${ne% *}"
-				es="${cmmttr#$ne}"
-				es="${es% *}"
-				es="${es# }"
 				obj="$(git rev-parse --verify --quiet --short "$newrev" --)"
 				extra=
 				[ "$type" = "tag" ] || [ -n "$notype" ] ||