t6421: fix test to work when repo dir contains d0

The `grep` statement in this test looks for `d0.*<string>`, attempting
to filter to only show lines that had tabular output where the 2nd
column had `d0` and the final column had a substring of
[`git -c `]`fetch.negotiationAlgorithm`. These lines also have
`child_start` in the 4th column, but this isn't part of the condition.

A subsequent line will have `d1` in the 2nd column, `start` in the 4th
column, and `/path/to/git/git -c fetch.negotiationAlgorihm` in the final
column. If `/path/to/git/git` contains the substring `d0`, then this
line is included by `grep` as well as the desired line, leading to an
effective doubling of the number of lines, and test failures.

Tighten the grep expression to require `d0` to be surrounded by spaces,
and to have the `child_start` label.

Signed-off-by: Kyle Lippincott <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: spectral54

t/t6421-merge-partial-clone.sh

@@ -230,8 +230,9 @@ test_expect_merge_algorithm failure success 'Objects downloaded for single relev
 		grep fetch_count trace.output | cut -d "|" -f 9 | tr -d " ." >actual &&
 		test_cmp expect actual &&
 
-		# Check the number of fetch commands exec-ed
-		grep d0.*fetch.negotiationAlgorithm trace.output >fetches &&
+		# Check the number of fetch commands exec-ed by filtering trace to
+		# child_start events by the top-level program (2nd field == d0)
+		grep " d0 .* child_start .*fetch.negotiationAlgorithm" trace.output >fetches &&
 		test_line_count = 2 fetches &&
 
 		git rev-list --objects --all --missing=print |
@@ -318,8 +319,9 @@ test_expect_merge_algorithm failure success 'Objects downloaded when a directory
 		grep fetch_count trace.output | cut -d "|" -f 9 | tr -d " ." >actual &&
 		test_cmp expect actual &&
 
-		# Check the number of fetch commands exec-ed
-		grep d0.*fetch.negotiationAlgorithm trace.output >fetches &&
+		# Check the number of fetch commands exec-ed by filtering trace to
+		# child_start events by the top-level program (2nd field == d0)
+		grep " d0 .* child_start .*fetch.negotiationAlgorithm" trace.output >fetches &&
 		test_line_count = 1 fetches &&
 
 		git rev-list --objects --all --missing=print |
@@ -422,8 +424,9 @@ test_expect_merge_algorithm failure success 'Objects downloaded with lots of ren
 		grep fetch_count trace.output | cut -d "|" -f 9 | tr -d " ." >actual &&
 		test_cmp expect actual &&
 
-		# Check the number of fetch commands exec-ed
-		grep d0.*fetch.negotiationAlgorithm trace.output >fetches &&
+		# Check the number of fetch commands exec-ed by filtering trace to
+		# child_start events by the top-level program (2nd field == d0)
+		grep " d0 .* child_start .*fetch.negotiationAlgorithm" trace.output >fetches &&
 		test_line_count = 4 fetches &&
 
 		git rev-list --objects --all --missing=print |