Make forced check-version asynchronous (again)

as it was before a34b8dab64.
Don't make zimfw hang in the foreground waiting for git to connect to
GitHub, mainly because the waiting can take too long in case of
connection issues or no network. Also set git timeout to 30 seconds so
background check also does hang for too long, just it case.

Fixes #514

src/stage2/50_zimfw_check_version.zsh.erb

@@ -1,14 +1,25 @@
 _zimfw_check_version() {
-  if [[ ${1} -ne 0 ]]; then
+  if (( ${1} )); then
     # Get latest version (get all `v*` tags from repo, delete `*v` from beginning,
     # sort in descending `O`rder `n`umerically, and get the `[1]` first)
+    if (( ${2} )); then
+      # background check
+      if [[ -w ${_zversion_target:h} ]]; then
+        print -R ${${(On)${(f)"$(GIT_HTTP_LOW_SPEED_LIMIT=1000 GIT_HTTP_LOW_SPEED_TIME=30 command git ls-remote --tags --refs \
+            https://github.com/zimfw/zimfw.git 'v*' 2>/dev/null)"}##*v}[1]} >! ${_zversion_target} &!
+      fi
+    else
+      # foreground check
       local tags
       tags=$(command git ls-remote --tags --refs https://github.com/zimfw/zimfw.git 'v*') || return 1
       >! ${_zversion_target} <<<${${(On)${(f)tags}##*v}[1]} || return 1
     fi
+  fi
+  if [[ -f ${_zversion_target} ]]; then
     local -r zlatest_version=$(<${_zversion_target})
     if [[ -n ${zlatest_version} && ${_zversion} != ${zlatest_version} ]]; then
       _zimfw_print -u2 -PR "%F{yellow}Latest zimfw version is %B${zlatest_version}%b. You're using version %B${_zversion}%b. Run %Bzimfw upgrade%b to upgrade.%f"
       return 4
     fi
+  fi
 }

src/stage2/80_zimfw.zsh.erb

@@ -49,7 +49,7 @@ Options:
   if ! zstyle -t ':zim' disable-version-check && [[ ${1} != check-version ]]; then
     # If .latest_version does not exist or was not modified in the last 30 days
     [[ -f ${_zversion_target}(#qNm-30) ]]; local -r zversion_check_force=${?}
-    _zimfw_check_version ${zversion_check_force}
+    _zimfw_check_version ${zversion_check_force} 1
   fi
 
   local _zrestartmsg=' Restart your terminal for changes to take effect.'

zimfw.zsh

@@ -386,18 +386,29 @@ _zimfw_check_dumpfile() {
 }
 
 _zimfw_check_version() {
-  if [[ ${1} -ne 0 ]]; then
+  if (( ${1} )); then
     # Get latest version (get all `v*` tags from repo, delete `*v` from beginning,
     # sort in descending `O`rder `n`umerically, and get the `[1]` first)
+    if (( ${2} )); then
+      # background check
+      if [[ -w ${_zversion_target:h} ]]; then
+        print -R ${${(On)${(f)"$(GIT_HTTP_LOW_SPEED_LIMIT=1000 GIT_HTTP_LOW_SPEED_TIME=30 command git ls-remote --tags --refs \
+            https://github.com/zimfw/zimfw.git 'v*' 2>/dev/null)"}##*v}[1]} >! ${_zversion_target} &!
+      fi
+    else
+      # foreground check
       local tags
       tags=$(command git ls-remote --tags --refs https://github.com/zimfw/zimfw.git 'v*') || return 1
       >! ${_zversion_target} <<<${${(On)${(f)tags}##*v}[1]} || return 1
     fi
+  fi
+  if [[ -f ${_zversion_target} ]]; then
     local -r zlatest_version=$(<${_zversion_target})
     if [[ -n ${zlatest_version} && ${_zversion} != ${zlatest_version} ]]; then
       _zimfw_print -u2 -PR "%F{yellow}Latest zimfw version is %B${zlatest_version}%b. You're using version %B${_zversion}%b. Run %Bzimfw upgrade%b to upgrade.%f"
       return 4
     fi
+  fi
 }
 
 _zimfw_clean_compiled() {
@@ -435,7 +446,7 @@ _zimfw_compile() {
 }
 
 _zimfw_info() {
-  print -R 'zimfw version:        '${_zversion}' (built at 2023-06-15 14:32:20 UTC, previous commit is f9648e0)'
+  print -R 'zimfw version:        '${_zversion}' (built at 2023-06-17 01:23:46 UTC, previous commit is 0566b9b)'
   local zparam
   for zparam in LANG ${(Mk)parameters:#LC_*} OSTYPE TERM TERM_PROGRAM TERM_PROGRAM_VERSION ZIM_HOME ZSH_VERSION; do
     print -R ${(r.22....:.)zparam}${(P)zparam}
@@ -885,7 +896,7 @@ Options:
   if ! zstyle -t ':zim' disable-version-check && [[ ${1} != check-version ]]; then
     # If .latest_version does not exist or was not modified in the last 30 days
     [[ -f ${_zversion_target}(#qNm-30) ]]; local -r zversion_check_force=${?}
-    _zimfw_check_version ${zversion_check_force}
+    _zimfw_check_version ${zversion_check_force} 1
   fi
 
   local _zrestartmsg=' Restart your terminal for changes to take effect.'