Merge branch 'rf/completion'

Completion updates.

* rf/completion:
  completion: add git config credentialCache.ignoreSIGHUP
  completion: add git config credential completions
  completion: add git config advice completions
  completion: add git config am.threeWay completion
  completion: add git config core completions
  completion: add git config gc completions

contrib/completion/git-completion.bash

@@ -2336,14 +2336,23 @@ _git_config ()
 	esac
 	__gitcomp "
 		add.ignoreErrors
+		advice.amWorkDir
 		advice.commitBeforeMerge
 		advice.detachedHead
 		advice.implicitIdentity
-		advice.pushNonFastForward
+		advice.pushAlreadyExists
+		advice.pushFetchFirst
+		advice.pushNeedsForce
+		advice.pushNonFFCurrent
+		advice.pushNonFFMatching
+		advice.pushUpdateRejected
 		advice.resolveConflict
+		advice.rmHints
 		advice.statusHints
+		advice.statusUoption
 		alias.
 		am.keepcr
+		am.threeWay
 		apply.ignorewhitespace
 		apply.whitespace
 		branch.autosetupmerge
@@ -2406,6 +2415,8 @@ _git_config ()
 		core.autocrlf
 		core.bare
 		core.bigFileThreshold
+		core.checkStat
+		core.commentChar
 		core.compression
 		core.createObject
 		core.deltaBaseCacheLimit
@@ -2415,6 +2426,8 @@ _git_config ()
 		core.fileMode
 		core.fsyncobjectfiles
 		core.gitProxy
+		core.hideDotFiles
+		core.hooksPath
 		core.ignoreStat
 		core.ignorecase
 		core.logAllRefUpdates
@@ -2422,20 +2435,30 @@ _git_config ()
 		core.notesRef
 		core.packedGitLimit
 		core.packedGitWindowSize
+		core.packedRefsTimeout
 		core.pager
+		core.precomposeUnicode
 		core.preferSymlinkRefs
 		core.preloadindex
+		core.protectHFS
+		core.protectNTFS
 		core.quotepath
 		core.repositoryFormatVersion
 		core.safecrlf
 		core.sharedRepository
 		core.sparseCheckout
+		core.splitIndex
+		core.sshCommand
 		core.symlinks
 		core.trustctime
 		core.untrackedCache
 		core.warnAmbiguousRefs
 		core.whitespace
 		core.worktree
+		credential.helper
+		credential.useHttpPath
+		credential.username
+		credentialCache.ignoreSIGHUP
 		diff.autorefreshindex
 		diff.external
 		diff.ignoreSubmodules
@@ -2467,15 +2490,19 @@ _git_config ()
 		format.thread
 		format.to
 		gc.
+		gc.aggressiveDepth
 		gc.aggressiveWindow
 		gc.auto
+		gc.autoDetach
 		gc.autopacklimit
+		gc.logExpiry
 		gc.packrefs
 		gc.pruneexpire
 		gc.reflogexpire
 		gc.reflogexpireunreachable
 		gc.rerereresolved
 		gc.rerereunresolved
+		gc.worktreePruneExpire
 		gitcvs.allbinary
 		gitcvs.commitmsgannotation
 		gitcvs.dbTableNamePrefix