[PATCH v2] t2400: Fix test failures when using grep 2.5

Replace all cases of `\s` with `[[:blank:]]` or ` ` as older versions of GNU grep (and from what it seems most versions of BSD grep) do not handle `\s`.

For the same reason all cases of `\S` are replaced with `[^ ]`. It's not an exact replacement (as it does not match tabs) but it is close enough for this use case.

Replacing `\S` also needs to occur as `\S` is technically PCRE and not part of ERE even though most modern versions of grep accept it as ERE.

This commit also drops `--sq` from a rev-parse call as it appears to be a no-op.

Signed-off-by: Jacob Abel <jacobabel@nullpo.dev>
---
This patch is in response to build failures on GGG's Cirrus CI 
freebsd_12 build jobs[1] and was prompted by a discussion thread [2].
These failures seem to be caused by the behavior outlined in [3]. 

Changes from v1:
  * Change `[[:space:]]` to ` ` where possible and `[[:blank:]]` 
    (tabs and spaces) otherwise as it is more accurate than `[[:space:]]` [4].
  * Change `[^[:space:]]` to `[^ ]` [4]. Technically `[^[:blank:]]` would be
    more accurate but tabs shouldn't be present where this `[^ ]` is used.
  * Drop `--sq` from rev-parse [4] (after further discussion [5]).
  * Update commit message to match changes.

1. https://github.com/gitgitgadget/git/pull/1550/checks?check_run_id=14949695859
2. https://lore.kernel.org/git/CALnO6CDryTsguLshcQxx97ZxyY42Twu2hC2y1bLOsS-9zbqXMA@mail.gmail.com/
3. https://stackoverflow.com/questions/4233159/grep-regex-whitespace-behavior
4. https://lore.kernel.org/git/vn5sylull5lqpitsanlyan5fafxj5dhrxgo6k65c462dhqjbno@uwghfyfdixtk/
5. https://lore.kernel.org/git/bj27nq5aputhd66rkqer37vuc7qogpmn6nqyusladdy4k5it7k@u3yvvivrixsy/

Range-diff against v1:
1:  39f57add45 ! 1:  ef4ebd7350 t2400: Fix test failures when using grep 2.5
    @@ Metadata
      ## Commit message ##
         t2400: Fix test failures when using grep 2.5
     
    -    Replace all cases of `\s` with `[[:space:]]` as older versions of GNU
    -    grep (and from what it seems most versions of BSD grep) do not handle
    -    `\s`.
    +    Replace all cases of `\s` with `[[:blank:]]` or ` ` as older versions
    +    of GNU grep (and from what it seems most versions of BSD grep) do not
    +    handle `\s`.
    +
    +    For the same reason all cases of `\S` are replaced with `[^ ]`. It's not
    +    an exact replacement (as it does not match tabs) but it is close enough
    +    for this use case.
     
    -    For the same reason all cases of `\S` are replaced with `[^[:space:]]`.
         Replacing `\S` also needs to occur as `\S` is technically PCRE and not
         part of ERE even though most modern versions of grep accept it as ERE.
     
    +    This commit also drops `--sq` from a rev-parse call as it appears to be
    +    a no-op.
    +
         Signed-off-by: Jacob Abel <jacobabel@nullpo.dev>
     
      ## t/t2400-worktree-add.sh ##
    @@ t/t2400-worktree-add.sh: test_wt_add_orphan_hint () {
      		if [ $use_branch -eq 1 ]
      		then
     -			grep -E "^hint:\s+git worktree add --orphan -b \S+ \S+\s*$" actual
    -+			grep -E "^hint:[[:space:]]+git worktree add --orphan -b [^[:space:]]+ [^[:space:]]+[[:space:]]*$" actual
    ++			grep -E "^hint:[[:blank:]]+git worktree add --orphan -b [^ ]+ [^ ]+$" actual
      		else
     -			grep -E "^hint:\s+git worktree add --orphan \S+\s*$" actual
    -+			grep -E "^hint:[[:space:]]+git worktree add --orphan [^[:space:]]+[[:space:]]*$" actual
    ++			grep -E "^hint:[[:blank:]]+git worktree add --orphan [^ ]+$" actual
      		fi
      
      	'
    @@ t/t2400-worktree-add.sh: test_dwim_orphan () {
      	local fetch_error_text="fatal: No local or remote refs exist despite at least one remote" &&
      	local orphan_hint="hint: If you meant to create a worktree containing a new orphan branch" &&
     -	local invalid_ref_regex="^fatal: invalid reference:\s\+.*" &&
    -+	local invalid_ref_regex="^fatal: invalid reference:[[:space:]]\+.*" &&
    ++	local invalid_ref_regex="^fatal: invalid reference: .*" &&
      	local bad_combo_regex="^fatal: '[a-z-]\+' and '[a-z-]\+' cannot be used together" &&
      
      	local git_ns="repo" &&
     @@ t/t2400-worktree-add.sh: test_dwim_orphan () {
    - 					headpath=$(git $dashc_args rev-parse --sq --path-format=absolute --git-path HEAD) &&
    + 					grep "$invalid_ref_regex" actual &&
    + 					! grep "$orphan_hint" actual
    + 				else
    +-					headpath=$(git $dashc_args rev-parse --sq --path-format=absolute --git-path HEAD) &&
    ++					headpath=$(git $dashc_args rev-parse --path-format=absolute --git-path HEAD) &&
      					headcontents=$(cat "$headpath") &&
      					grep "HEAD points to an invalid (or orphaned) reference" actual &&
     -					grep "HEAD path:\s*.$headpath." actual &&
     -					grep "HEAD contents:\s*.$headcontents." actual &&
    -+					grep "HEAD path:[[:space:]]*.$headpath." actual &&
    -+					grep "HEAD contents:[[:space:]]*.$headcontents." actual &&
    ++					grep "HEAD path: .$headpath." actual &&
    ++					grep "HEAD contents: .$headcontents." actual &&
      					grep "$orphan_hint" actual &&
      					! grep "$info_text" actual
      				fi &&

 t/t2400-worktree-add.sh | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)