t1512: correct leftover constants from earlier edition

The earliest iteration of this test script used a magic string
110282 as the common prefix for ambiguous object names, but the
final edition switched the common prefix to 0000000000 (10 "0"s).

Unfortunately, instances of the original prefix were left in the
comments and a few tests.  Replace them with the correct constants.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t1512-rev-parse-disambiguation.sh

@@ -77,6 +77,7 @@ test_expect_success 'disambiguate blob' '
 
 test_expect_success 'disambiguate tree' '
 	commit=$(echo "d7xm" | git commit-tree 000000000) &&
+	# this commit is fffff2e and not ambiguous with the 00000* objects
 	test $(git rev-parse $commit^{tree}) = $(git rev-parse 0000000000cdc)
 '
 
@@ -99,10 +100,14 @@ test_expect_success 'disambiguate commit-ish' '
 
 test_expect_success 'disambiguate commit' '
 	commit=$(echo "hoaxj" | git commit-tree 0000000000cdc -p 000000000) &&
+	# this commit is ffffffd8 and not ambiguous with the 00000* objects
 	test $(git rev-parse $commit^) = $(git rev-parse 0000000000e4f)
 '
 
 test_expect_success 'log name1..name2 takes only commit-ishes on both ends' '
+	# These are underspecified from the prefix-length point of view
+	# to disambiguate the commit with other objects, but there is only
+	# one commit that has 00000* prefix at this point.
 	git log 000000000..000000000 &&
 	git log ..000000000 &&
 	git log 000000000.. &&
@@ -112,16 +117,19 @@ test_expect_success 'log name1..name2 takes only commit-ishes on both ends' '
 '
 
 test_expect_success 'rev-parse name1..name2 takes only commit-ishes on both ends' '
+	# Likewise.
 	git rev-parse 000000000..000000000 &&
 	git rev-parse ..000000000 &&
 	git rev-parse 000000000..
 '
 
 test_expect_success 'git log takes only commit-ish' '
+	# Likewise.
 	git log 000000000
 '
 
 test_expect_success 'git reset takes only commit-ish' '
+	# Likewise.
 	git reset 000000000
 '
 
@@ -131,26 +139,30 @@ test_expect_success 'first tag' '
 '
 
 test_expect_failure 'two semi-ambiguous commit-ish' '
+	# At this point, we have a tag 0000000000f8f that points
+	# at a commit 0000000000e4f, and a tree and a blob that
+	# share 0000000000 prefix with these tag and commit.
+	#
 	# Once the parser becomes ultra-smart, it could notice that
-	# 110282 before ^{commit} name many different objects, but
+	# 0000000000 before ^{commit} name many different objects, but
 	# that only two (HEAD and v1.0.0 tag) can be peeled to commit,
 	# and that peeling them down to commit yield the same commit
 	# without ambiguity.
-	git rev-parse --verify 110282^{commit} &&
+	git rev-parse --verify 0000000000^{commit} &&
 
 	# likewise
-	git log 000000000..000000000 &&
-	git log ..000000000 &&
-	git log 000000000.. &&
-	git log 000000000...000000000 &&
-	git log ...000000000 &&
-	git log 000000000...
+	git log 0000000000..0000000000 &&
+	git log ..0000000000 &&
+	git log 0000000000.. &&
+	git log 0000000000...0000000000 &&
+	git log ...0000000000 &&
+	git log 0000000000...
 '
 
 test_expect_failure 'three semi-ambiguous tree-ish' '
 	# Likewise for tree-ish.  HEAD, v1.0.0 and HEAD^{tree} share
 	# the prefix but peeling them to tree yields the same thing
-	git rev-parse --verify 000000000^{tree}
+	git rev-parse --verify 0000000000^{tree}
 '
 
 test_expect_success 'parse describe name' '
@@ -241,7 +253,7 @@ test_expect_success 'ambiguous commit-ish' '
 	# Now there are many commits that begin with the
 	# common prefix, none of these should pick one at
 	# random.  They all should result in ambiguity errors.
-	test_must_fail git rev-parse --verify 110282^{commit} &&
+	test_must_fail git rev-parse --verify 00000000^{commit} &&
 
 	# likewise
 	test_must_fail git log 000000000..000000000 &&